- Change "Estimated EoL" to "Expected EoL".

- Rephrase the explanation for the EoL table.  Most significantly,
  remove any suggestion that we may terminate a release earlier than
  the announced date.

- Remove all mention of "early adopter" releases.  We've only ever had
  one, and that was more than ten years ago.

- Mention that BETA and RC releases are supported for a few weeks "as
  resources permit".


git-svn-id: svn+ssh://svn.freebsd.org/doc/head@45733 c2e8774f-c49f-e111-b436-862b2bbc8956