Add exclusive backup deprecation notes to documentation

When Who What
2019-03-29 15:43:34 Peter Eisentraut (petere) Closed in commitfest 2019-03 with status: Committed
2019-03-29 15:43:34 Peter Eisentraut (petere) Changed committer to rhaas
2019-03-07 12:26:50 David Steele (dsteele) New status: Needs review
2019-03-04 03:37:50 Michael Paquier (michael-kun) New status: Waiting on Author
2019-03-01 11:10:18 Martín Marqués (mmarques) New status: Ready for Committer
2019-02-28 19:07:05 Martín Marqués (mmarques) Added mmarques as reviewer
2019-02-28 18:03:03 David Steele (dsteele) Changed authors to David Steele (dsteele)
2019-02-28 18:03:03 David Steele (dsteele) Changed targetversion to 12
2019-02-28 18:02:46 David Steele (dsteele) Attached mail thread 7d85c387-000e-16f0-e00b-50bf83c22127@pgmasters.net
2019-02-28 18:02:46 David Steele (dsteele) Created patch record