Обсуждение: pgsql: Improve mmgr README.

Improve mmgr README.

Add documentation about the new reset callback mechanism.

Also, at long last, recast the existing text so that it describes the
current context mechanisms as established fact rather than something
we're going to implement.  Shoulda done that in 2001 or so ...

Branch
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master

Details
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http://git.postgresql.org/pg/commitdiff/c4f4c7ca99169ac609df67c2d0eb78162484420c

Modified Files
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src/backend/utils/mmgr/README |  234 ++++++++++++++++++++++-------------------
1 file changed, 123 insertions(+), 111 deletions(-)