remove non-free leanpub books (#7026)

* remove non-free leanpub books

45 books removed, the 59 books remaining are still free.

* re-add 5, fix 3

a programmed scan of the leanpub urls reveal 5 that should not have been removed and 3 that should use /read urls

* revert to previous index structure

books/free-programming-books-tr.md

@@ -17,7 +17,6 @@
 * [Linux](#linux)
 * [Matlab](#matlab)
 * [.NET Framework](#net-framework)
-* [PHP](#php)
 * [Python](#python)
     * [Django](#django)
 * [R](#r)
@@ -126,11 +125,6 @@
 * [ASP.NET Core El Kitabı](https://sahin.gitbook.io/asp-net-core-el-kitab)
 
 
-### PHP
-
-* [PHP - Laravel 4 Türkçe Dokumantasyon](https://www.leanpub.com/laravel4-tr)
-
-
 ### Python
 
 * [Bilgisayar Bilimcisi Gibi Düşünmek-Python3 ile Öğrenme](https://www.ofenerci.github.io/thinkcspy-tr) - Peter Wentworth, Jeffrey Elkner, Allen B. Downey ve Chris Meyers