Add new 'UX-Advice' component to the BSA

This commit enables/adds the new 'UX-Advice' component to the BSA.

Note: Before you can add a new component to the BSA, you'll need to
create the appropriate set of documentation wiki pages under
QA/Bugzilla/Components/<component-name>/. Just crib mercilessly from
one that's already there. The templates make things much easier...