* Added codechef's problem set

A vast range of unique problems, some of which are also part of Indian ICPC Preliminary Rounds and Regionals Rounds.

* Added codedrills' comeptitive problem set

Codedrills is the platform responsible for Indian ICPC contests currently (from 2020-present). It has many original & pure algorithmic problems.

* added sinhala courses

* updateted free-courses-sl.md

* free-courses-sl.md updated v2

* Update courses/free-courses-sl.md

Update courses/free-courses-sl.md v3
Co-authored-by: NDavid Ordás <3125580+davorpa@users.noreply.github.com>

* Update courses/free-courses-sl.md

Update courses/free-courses-sl.md v4
Co-authored-by: NDavid Ordás <3125580+davorpa@users.noreply.github.com>

* Update courses/free-courses-sl.md v5

Update courses/free-courses-sl.md v5
Co-authored-by: NDavid Ordás <3125580+davorpa@users.noreply.github.com>

* Update courses/free-courses-sl.md

Update courses/free-courses-sl.md v6
Co-authored-by: NDavid Ordás <3125580+davorpa@users.noreply.github.com>

* Update courses/free-courses-sl.md

Update courses/free-courses-sl.md v6
Co-authored-by: NDavid Ordás <3125580+davorpa@users.noreply.github.com>

* Update courses/free-courses-sl.md

Update courses/free-courses-sl.md v7
Co-authored-by: NDavid Ordás <3125580+davorpa@users.noreply.github.com>

* Update courses/free-courses-sl.md

Update courses/free-courses-sl.md v8

* updated free-courses-sl.md 

resolved empty catogory
Co-authored-by: NDavid Ordás <3125580+davorpa@users.noreply.github.com>

* add french javascript course

* fix url
Co-authored-by: Nx0rld <git@x0rld.eu>

* new farsi kotlin course added

* 2 more courses were added in kotlin section
Co-authored-by: NEmad Ehsanrad <emad.ehsanrad@gmail.com>

* Added two Electronjs courses Resolves #5928

* updated links and category

* Added new resources for MySQL in Bengali

* Sorted lines alphabetically

* Added vertical tab scape and fixed instructor name for sohidul islam
Co-authored-by: NDavid Ordás <3125580+davorpa@users.noreply.github.com>

* Added instructor name for "live project"
Co-authored-by: NDavid Ordás <3125580+davorpa@users.noreply.github.com>

* Fix names and add platform
Co-authored-by: NDavid Ordás <3125580+davorpa@users.noreply.github.com>

* add svelte interactive tutorial

* add svelte courses

* add svelte to index

* move svelte resource to books listing

* move svelte resource to courses

Foram retirados alguns links da Udemy para cursos pagos.

Precisa checar os cursos das demais linguagens, não pude fazer isso.
Provavelmente os demais cursos Udemy que ainda são gratuitos se tornarão pagos no futuro, e deverão ser removidos da lista quando isso acontecer.

Provavelmente este repositório está sendo usado para SEO e SEM. Portanto, sugiro que seja discutida a inserção de links para empresas que alteram a visibilidade de cursos que, no início são gratuitos e, posteriormente são alterados para pagos, fazendo com que esse repositório sirva para publicidade gratuita.

* translate HOWTO to Vietnamese

* Addition notes

* Update CONTRIBUTING.md

Made a spelling correction, for better understanding

* Apply suggestions from code review
Co-authored-by: NDavid Ordás <3125580+davorpa@users.noreply.github.com>
Co-authored-by: NDavid Ordás <3125580+davorpa@users.noreply.github.com>

* Restructured the Books to add new Subsection : MongoDB and added The Definitive Guide to MongoDB PDF book

* Ordered the MongoDb list

* Updated new link for free book

* Added new resource about web development

* Added note about email requirement

* Add resources about algorithms from UNAM

## What does this PR do?
Add free resource about algorithms from UNAM
 
## For resources
### Description
Handbook used in the online program of UNAM (SUAyED) for algorithms assignatures covering topics such as: algorithms concepts and properties, automatan, fomal programming languages and Turing machine.
### Why is this valuable (or not)?
This PR adds free material from the most pretigious college in México that is used in it's asignatures.
 
### How do we know it's really free?
It's provided from UNAM's official website.
 
### For book lists, is it a book? For course lists, is it a course? etc.
Yes, for the book lists it is a book.

## Checklist:
* [x]  Read our [contributing guidelines](https://github.com/EbookFoundation/free-programming-books/blob/master/CONTRIBUTING.md)
* [x]  Search for duplicates.
* [x]  Include author(s) and platform where appropriate.
* [x]  Put lists in alphabetical order, correct spacing.
* [x]  Add needed indications (PDF, access notes, under construction)
 
## Follow-up
* Check the status of GitHub Actions and resolve any reported warnings!

* Fixed alphabetical order of the contribution

* Correction quoting source and authors

* add electron book from syncfusion

* change electron category to javascript framework

* remove .idea folder

* fix error linting in electron resources

* rearrange korean course in alphabetical order

* change section according to the markdown syntax

* Add new section and book: operation system

* HTML syntax back to its original state.

* changed to direct link

* Update free-programming-playgrounds.md

Added a few C++ playgrounds to the list

* Update free-programming-playgrounds.md

Placed the links in alphabetical order. I mistakenly didn't do this in my initial PR.

* Added respective authors to the links

* Update more/free-programming-cheatsheets.md
Co-authored-by: NDavid Ordás <3125580+davorpa@users.noreply.github.com>
Co-authored-by: NDavid Ordás <3125580+davorpa@users.noreply.github.com>

* add gtk event driven book

* update with correct book name
Co-authored-by: NDavid Ordás <3125580+davorpa@users.noreply.github.com>
Co-authored-by: NDavid Ordás <3125580+davorpa@users.noreply.github.com>

* Add flutter/dart courses in arabic

I added new sections for Flutter and Dart courses
provided by eng.Asem Saafan

* Add flutter/dart courses in arabic

I added new sections for Flutter and Dart courses
provided by eng.Asem Saafan

* Add flutter/dart courses in arabic

I added new sections for Flutter and Dart courses
provided by eng.Asem Saafan

* Add flutter/dart courses in arabic

I added new sections for Flutter and Dart courses
provided by eng.Asem Saafan

Co-authored-by: NAdain, Mohammed Wazir <adain@deshaw.com>

* Improve german HOWTO file by fixing some grammar and restructuring some sentences to make it easier to read and understand

* Improve german CONTRIBUTING file by fixing some grammar and fix some readability issues

* Added a non-breaking space for "z. B." to prevent automatic line break

* Restore alignment on good/bad examples with colons

* Adding Database Systems free Course

Add youtube video's URL with Database Systems - Cornell University Course (SQL, NoSQL, Large-Scale Data Analysis) subject that created by Professor Immanuel Trummer, PhD and uploaded in the  freeCodeCamp.org youtube channel

* Update courses/free-courses-en.md with better name resources and simpler attributions

Implement the advice about name resources and complex attributions.
Co-authored-by: NDavid Ordás <3125580+davorpa@users.noreply.github.com>
Co-authored-by: NDavid Ordás <3125580+davorpa@users.noreply.github.com>

* Adding Module Patterns

* Update books/free-programming-books-langs.md
Co-authored-by: NDavid Ordás <3125580+davorpa@users.noreply.github.com>
Co-authored-by: NDavid Ordás <3125580+davorpa@users.noreply.github.com>

by Pepcoding

* Korean guide upload

* Korean guide upload

* Language link update
Co-authored-by: Nhedykim <mzchedykim@lgupluspartners.co.kr>

Enhance format CONTRIBUTING-id.md for more readable according to Git format

Adding new youtube playlist for Git Free Course from Eko Kurniawan Khannedy, Programmer Zaman Now (YouTube)

Introduction to Compilers and Language Design - Douglas Thain (PDF)