Add tooltips

[digitalfiz]

Also suggested by @buildersbrewery

Example code:

• https://github.com/atom/styleguide

Reference:

• http://code.google.com/p/kwdb/source/browse/database/kwdb.xml
• https://github.com/buildersbrewery/lsl-for-notepadplusplus/blob/master/Notepad++/plugins/APIs/lsl.xml
• https://bitbucket.org/oz_linden/storm-1831/src/default/indra/newview/app_settings/keywords_lsl_default.xml

[ghost]

Tooltips code for Atom is (as of right now) described here:

https://github.com/atom/styleguide/blob/7164a09b9412ee5343d20da9ce3ae44b19f885b0/lib/styleguide-view.coffee#L560-L577

[buildersbrewery]

Current reference:

https://github.com/atom/styleguide/blob/2bc779dfc27afcccef1c0b6c25f6a4ab5f9f00bf/lib/styleguide-view.js#L1141-L1162