* Add FreeRTOS book

Resolves part of EbookFoundation/free-programming-books/issues/5466

* Move FreeRTOS book to Embedded Systems

Resolves part of EbookFoundation/free-programming-books#5466

* Add DigiKey's RTOS course

Resolves part of EbookFoundation/free-programming-books#5466

* Fix obsolete Microsoft edX courses

Solves part of EbookFoundation/free-programming-books#5112

* Fix with stable alternative for "Hg Init" guide

Solves part of EbookFoundation/free-programming-books#5112

@hginit https://github.com/hginit/hginit.github.ioCo-authored-by: Nhginit <hginit@captnemo.in>
Co-authored-by: Ncaptn3m0 <github.contact@captnemo.in>

* Use wayback machine to recover FindLectures.com

Solves part of EbookFoundation/free-programming-books#5112

Only works first page of mirror
Co-authored-by: Nhginit <hginit@captnemo.in>
Co-authored-by: Ncaptn3m0 <github.contact@captnemo.in>

* Updated a Java Course

* Update free-courses-en.md

* Added more Python resources, updated links/info

* Corrected sorting order

* Removed courses from book list

* Added two Python courses, http to https

* adding web dev curriculum, 24 lessons

* fix

* Add data visualization course 2020

* Sorted and removed YouTube tags

* reorganize files

1. make it easier to find files
2. reduce scrolling to get to README on main view of repo

* remove tr.txt again

* fixes #4358

* Update title to match source

* remove duplicates

* add from #4941

* Cleaned up some broken links and updated few links and provided new books list

* cleaned up broken links and added new and updated links

* Modified and added new links

* delete an editor file

* we don't permit shortened links

* replace AngularJS channel links

* fix spacing, add title from resource

* remove duplicate

* moved "software engineering" courses to java and RoR

* attribution, title from resource

* alphabetize
Co-authored-by: NEric Hellman <eric@hellman.net>

* Adding french file with +100 courses and adding content in english free courses

* moved courses-fr file to #5151

* delint

* fix joined lines

* delint

* duplicate in interactive tutorials

* link to full LearnSQL, omit non-playlist

omit learn SQL in 60 minutes because not long enough a course

* omit non-playllist

* another non-playlist

* use title from resource
Co-authored-by: NAdam Zebiche <contact@ethernily.fr>
Co-authored-by: NEric Hellman <eric@hellman.net>

* Add HTTPS and JS resources, check_urls=free-programming-books.md free-courses-en.md

* moved http and https sections into networking
Co-authored-by: NEric Hellman <eric@hellman.net>

* Update free-courses-en.md

* Update free-courses-en.md

* Update free-courses-en.md

* alphabetize
Co-authored-by: NEric Hellman <eric@hellman.net>

* Add D3.js courses, check_urls=free-courses-en.md

* Add d3.js courses, check_urls=free-courses-en.md

Co-authored-by: NEric Hellman <eric@hellman.net>

* Remove Duplicate LearnCpp.com

* Rename LearnCpp.com

* Add Markdown, check_urls=HOWTO.md

* Add Git course, check_urls=free-courses-en.md