Update free-programming-books.md

Fixed typo.
[en] Adding Perl Book (and removing Perl 6 duplicated)
Merge pull request #767 from esparta/master

[en] Adding Perl Book (and removing Perl 6 duplicated)
Sort scheme
Sort html/css
Sort iOS
Merge pull request #789 from Mouseion/patch-sort

Fix sorting
Update free-programming-books.md
[es] Adding .NET book
Merge branch 'master' of github.com:vhf/free-programming-books
Merge pull request #790 from wzhishen/master

added tutorial entries for Prolog
Merge pull request #791 from esparta/master

[es] New .NET book
[es] New Scala section with 2 book
Merge pull request #792 from esparta/master

[es] New Scala section with 2 book
Go Kaynağı Eklendi
Merge pull request #793 from msdundar/patch-1

Go Kaynağı Eklendi
[en] Added a .NET book
[en] Ording .Net section
Merge pull request #794 from esparta/master

[en] New book on .NET section & sorting
[en] Added CS240h: Functional Systems in Haskell