Merge branch 'master' of github.com:vhf/free-programming-books
Merge remote-tracking branch 'central/master'
Merge remote-tracking branch 'central/master'
Merge remote-tracking branch 'central/master'
Sorting Flex section & minimal markdown fix
[en] Sorting Force section
[en] Sorting Forth section
Merge pull request #939 from JIghtuse/master

Add Think OS book (greenteapress)
add book "Programming in Martin-Löf's Type Theory" by Bengt Nordström
Merge pull request #940 from AndriyLin/master

add book "Programming in Martin-Löf's Type Theory" by Bengt Nordström
Added OpenStack Operations Guide
Merge pull request #941 from marios-zindilis/master

Added OpenStack Operations Guide
[en] Sorting iOS section
Add 沉浸式学 Git http://igit.linuxtoy.org/index.html
Merge pull request #942 from viztor/patch-1

Add 沉浸式学 Git http://igit.linuxtoy.org/index.html
Add Node.js Succinctly book.
Merge pull request #943 from levibostian/nodejs

Add Node.js Succinctly book.
[en] Sorting J section
Merge pull request #944 from esparta/master

[en] Sorting some sections on english books
[es] Added Database book