pgsql: doc PG 18 relnotes: update to current

doc PG 18 relnotes: update to current

Includes runtime injection point item by Michael Paquier.

Reported-by: Michael Paquier

Author: Michael Paquier

Discussion: /messages/by-id/aDAS0_eWzeGl4sok@paquier.xyz

Branch
------
master

Details
-------
https://git.postgresql.org/pg/commitdiff/1ca583f6c0f9c178dd2721886c723791ced65520

Modified Files
--------------
doc/src/sgml/release-18.sgml | 22 ++++++++++++++++++++--
1 file changed, 20 insertions(+), 2 deletions(-)