Added dev tools and third-party modules sections

Also added Ionic to mobile section
Update README.md

Added another Youtube Channel Collection.
Update README.md

Updated Another Youtube channel in the Videos
Added markdown tablet of contents
typo fix
Merge pull request #95 from jelinson/toc

Table of Contents
Merge pull request #94 from vigneshshanmugam/master

Added another youtube videos collection in the Videos list.
Merge pull request #93 from jelinson/en-additions

Added dev tools and third-party modules sections
Update README.md

added a couple of new links