Update free-programming-books.md

Added C# book
Update free-programming-books-pl.md
Merge pull request #478 from zawieja/master

Update pl.md : C++
en : Ubuntu Server Guide
Add portuguese translation of "XP from the Trenches", Kniberg
Add japanese translation of "Scrum and XP from the Trenches", Kniberg
Add chinese translation of "Scrum and XP from the Trenches", Kniberg
Fix anchors (persian)
Fix a link
Merge pull request #481 from ericguirbal/fr

Fix a link
Merge pull request #480 from ericguirbal/fix-anchors

Fix anchors (persian)
Merge pull request #479 from ericguirbal/kniberg

Translated versions of "Scrum and XP from the Trenches" in japanese, chinese and portuguese
LaTeX and Persian Conflict
Merge pull request #483 from MHM5000/master

LaTeX and Persian Conflict $482
Reorders the "Non dépendant du langage" section

- Add navigation links
- Sort by alphabetical order
Merge pull request #484 from ericguirbal/fr

Reorders the "Non dépendant du langage" section
C#
Merge remote-tracking branch 'upstream/master'
Added Node.js Removed ad
Merge pull request #485 from mobi-soft/patch-2

Added Node.js Removed ad