pgsql: Remove INCLUDE attributes section from docs.

Remove INCLUDE attributes section from docs.

Discussing covering indexes in a chapter that is mostly about the
behavior of B-Tree operator classes is unnecessary. The CREATE INDEX
documentation's handling of covering indexes seems sufficient.

Discussion: /messages/by-id/CAH2-WzmpU=L_6VjhhOAMfoyHLr-pZd1kDc+jpa3c3a8EOmtcXA@mail.gmail.com

Branch
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master

Details
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https://git.postgresql.org/pg/commitdiff/514d4a1338d5409431d644eaf453193ac362ef16

Modified Files
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doc/src/sgml/btree.sgml | 17 -----------------
1 file changed, 17 deletions(-)