pgsql: Update comment of AlterTableCmd->name in parsenodes.h

Update comment of AlterTableCmd->name in parsenodes.h

Since b0483263dda0, this field can be used to store an access method
name for ALTER TABLE, but access methods were not mentioned in the
field's description.

Issue noticed while working on the area.

Discussion: /messages/by-id/ZeWKgCtk6xiAsDsc@paquier.xyz

Branch
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master

Details
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https://git.postgresql.org/pg/commitdiff/4f8c1e7aaf11c42fa658eeab9baef0a035e76fe2

Modified Files
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src/include/nodes/parsenodes.h | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)