status/README: Fix phrasing, paths, news example, and nits.

Summary:
Move sections of the README around a bit, so that it becomes clearer
what belongs where.
Avoid repeating instructions too much, as this makes it more difficult.
Make the timeline easier to get information from at a glance.

While here, fix minor typos, grammatical errors and whitespace errors.

Reviewed by: PauAmma
Differential Revision: https://reviews.freebsd.org/D28179