Identify pg_replication_origin as a shared catalog in catalogs.sgml,
using the same boilerplate wording used for most other shared catalogs
(and tweak another place where someone had randomly deviated from
that boilerplate).

Make an example in mmgr/README more consistent with surrounding text.

Update an obsolete cross-reference in a comment in storage/block.h.

Zhuo Ql

Discussion: https://postgr.es/m/44296255.1819230.1524889719001@mail.yahoo.com