pgsql: Move PITR and StreamingRep up one level of heading in the 9.1 re

Move PITR and StreamingRep up one level of heading in the 9.1 release
notes.

Remove excessive linking to pg_ctl manual page.

Reorder incompatibility sections.

Branch
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master

Details
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http://git.postgresql.org/pg/commitdiff/c2f4ea469b52e6f7fedff651a4aa0acced873a5f

Modified Files
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doc/src/sgml/release-9.1.sgml | 446 ++++++++++++++++++++---------------------
1 files changed, 222 insertions(+), 224 deletions(-)