pgsql: Doc fix: Interfacing Extensions to Indexes

Doc fix: Interfacing Extensions to Indexes

Refer to CREATE ACCESS METHOD rather than suggesting direct changes to
pg_am. Also corrects index-specific language that predated table
access methods.

Discussion: https://postgr.es/m/20231025172551.685b7799455f9a6addcf5afa@sraoss.co.jp
Reported-by: Yugo NAGATA <nagata@sraoss.co.jp>

Branch
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master

Details
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https://git.postgresql.org/pg/commitdiff/e9d12a5e22e02bace45dc2ba0e0dcca5b5d4fc52

Modified Files
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doc/src/sgml/xindex.sgml | 13 +++++--------
1 file changed, 5 insertions(+), 8 deletions(-)