Summary:
Merge branch 'master' of https://github.com/lubuntu-team/manual
1.3 Images added
deleted uneeded images
Fixed minor typos raise in tsimons concerns.
Minor changes, removed test Renamed discover to Discover software center.
removed test
Added a section for software management. Added tags to help search in documentation.
Test Plan: Sample test
Differential Revision: https://phab.lubuntu.me/D39
