Improve documentation for QmlLive Usage Options

Currently, the options' documentation are copied from the terminal. Since we are a bit short on time for 5.12.1, this ticket is to make sure that we revisit this documentation in time for the next release.

Ideally, all the options should be in a table with documentation in full sentences. 

This is the patch where we discussed the issue: https://codereview.qt-project.org/#/c/253562/