pgsql: Doc: undo mistaken adjustment to LOCK TABLE docs in back branche

Doc: undo mistaken adjustment to LOCK TABLE docs in back branches.

Commits 59ab4ac32 et al mistakenly copied-and-pasted some text about
how LOCK on a view recurses to referenced tables into pre-v11 branches,
which in fact don't do that. Undo that, and instead state clearly
that they don't. (I also chose to add a note that this behavior
changed in v11. We usually don't back-patch such statements, but
since it's easy to add the warning now, might as well.)

Noted while considering followup fixes for bug #16703.

Discussion: https://postgr.es/m/16703-e348f58aab3cf6cc@postgresql.org

Branch
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REL9_5_STABLE

Details
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https://git.postgresql.org/pg/commitdiff/8b4121903c2d7deca4a7041af791ede46597f9dd

Modified Files
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doc/src/sgml/ref/lock.sgml | 9 +++++++--
1 file changed, 7 insertions(+), 2 deletions(-)