Document Filter Scheduler and overcommit ratio

Terminology: add "Scheduler" and "Overcommit ratio" articles.

User guide: add section with graphic for Settings page where one
can select the older scheduler

Release Notes: add sections for "Filter Scheduler" and "Overcommit ratio"
to 030-other-enhancements

Change-Id: Ie48d69461da1427d31b67f916d5e1a2abed95e91
Closes-Bug: 1333436