Added reviewed books compiled from from StackOverflow documentation

* Please add Django 2.0 Online Book

I would like to add this online book of Django 2.0 to the list.

Thanks in advance.

* Django 2.0 Tutorial for Beginners

Removed slash "/" at the end of link.
(Although several other links contain it)

* Added JavaScript/Redux 

1. Added new section to JavaScript (Redux) 
2. Add the "The Complete Redux Book" to the list

* add required spaces, add account required notation

* Please add a new Python Book

I found this new book just released in January 2018.
It is a compilation from StackOverflow documentation and is freely available.

Thanks.

* Please add new Python book

Changes made.

* nit

* Add GLib/GTK+ Development Platform book.

The books is licensed under a Creative Commons Attribution-ShareAlike 4.0
International License:
https://creativecommons.org/licenses/by-sa/4.0/

* Put link in order.

* Add pdf indicator.

"Java: A Beginner's Guide" is just the first chapter of a book
"NIO Framework" is a 6 page paper, also not a book

It pointed to a tutorial and not to the book.

remove the link to "Operating Systems Concept 9th edition" because it is not a book, but a bunch of slides (#2674)

* Update free-courses-en.md

Added a Python online resource under the Python course section.

* Update free-programming-books.md

Added techbeamers to meta-list section.

* fixed link

* remove trailing slash to satisfy linter

* Added Microservice Databases: Migrating from Relational Monolith to Distributed Data (By O'Reilly)

* fixed concerns

* Added the bash book to the books section

I have attempted to add the bash book to the book section again. There was  an issue the last time , i tried to propose the file change as i had not placed it in alphabetical order. Someone please review this :)

* fixed alphabetization

* Add couple of book for PHPUnit

* Added PDF text to the links

* Added PHPUnit Best Practices

* Alphabetically arranged

* [JavaScript and Node FUNdamentals](https://web.archive.org/web/20150327025334/https://leanpub.com/jsfun/read) - Azat Mardanov is not a free programming book

* implement #2357

* misc cleanup

Author deleted page partially.
He write message on the page: This book has been removed as it will shortly be published by APress.

*  added link to Directory of free Javascript ebooks

* link fix Directory of free Javascript ebooks and sorting in alphabetical order

* updated link

*  Sorry, Corrigir e retirei o link

* Revert "correcting and removing the link

This reverts commit 5059e43931299d7fcdd017ae53c8c742ea36dd1f.

* Clean up the Oberon books

The Project Oberon book was duplicated under both Operating Systems and
Misc; plus a better link for Programming in Oberon.

* Add direct PDF links and authors for Oberon books

* Update free-programming-books.md

Added Django Girls tutorial. Since it's not an interactive tutorial i have added it to books section.

* Update free-programming-books.md

Moved Django Girls Tutorial to the top of the Django books list according to alphabetic order.

* Add Procedural Content Generation in Games

* Remove trailing slash

Remove trailing slash to fix a CI-flagged error.

* update verilog

update a free source of verilog quick reference

* substituted authoritative source for the quick reference guide

(PR has been sitting for a year)

added Funtional C ; free download & more info at https://research.utwente.nl/en/publications/functional-c (#2613)

* Replace homepage with GitHub repository link

problem-sets-competitive-programming.md: Replace homepage
link of problembook with github repository link which contains
downloadable pdf links.

* Remove broken links

Remove broken links and update available links from
web.archive.org.

* Update broken link with updated link.

Update the description for the updated link.

* Update broken links with links from web.archive.org

Remove dead links.

* Restore path to original link instead of web.archive.org

The link seems to be working fine. It was not loading
on my network, probably due to regional restrictions.

* Remove github link which is no longer maintained.

Github link consisted of list of Big Data resources.
The repository has been deleted by the user.
Hence deleting the entry.

* Add Clojure by Example

It's an example-based alternative to reading a long, in-depth book.

* Fix alphabetic order from last commit

Clojure section addition in wrong position.

* Add author to clojure by example

* Update Gambas links

Updated broken Gambas beginner's guide link, and add additional link to Gambas resources since the original book's website has been taken down

* removed gambas links

Not sure the book is free anymore, and realised second link doesn't comply with contribution guidelines as it's not an actual book

* Re-add beginner's guide to gambas

* R: Add Introduction to Statistical Learning by Hastie et al

* R: sort alphabetically

* add hack language

closes #2097

* Whoops! Wrong list.

* aaaaarg

* add notations for bookboon

* satisfy linter

Unofficial PDF version of "Category Theory for Programmers" by Bartosz Milewski, converted from his blogpost series. Blog content licensed as CC BY 4.0 International as seen at https://bartoszmilewski.com/about/