Update free-programming-books.md

Added a link to "Models of Computation" by John E. Savage to the
"Theoretical Computer Science" category.
'R' Language in Persian/Farsi
'R' Language in Spanish
Res: http://cran.r-project.org/other-docs.html
Enhance Readme
Indexing 'R' in Spanish
Fix cliffnotes markdown link
Merge pull request #436 from Stevo-S/patch-1

Update free-programming-books.md
Merge pull request #437 from MHM5000/master

R language & Enhancement
Merge pull request #438 from nesquena/patch-2

Fix cliffnotes markdown link
TODO
TODO Update1: Wiki:2Obj, Readme:4Obj
Better UI/UX with the Headings/ULs
changing fa to fa_IR
Ugrading TODO
Simplest and useful links
Merge pull request #439 from MHM5000/master

Upgrading the Structure of files