pgsql: Doc: hack table 13.2 "Conflicting Lock Modes" till it fits in PD

Doc: hack table 13.2 "Conflicting Lock Modes" till it fits in PDF.

I can't see any way to make this table fit in PDF column width
without either a fundamental redesign or abbreviating EXCLUSIVE.
So I did the latter.

It'd be nicer if the abbreviating didn't leak into the HTML output
as well; but the hackery required to make the output different
seems like more trouble than it's really worth.

Discussion: https://postgr.es/m/6916.1589146280@sss.pgh.pa.us

Branch
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master

Details
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https://git.postgresql.org/pg/commitdiff/57775e82b235b2c815d9fd85cea53d77373a9203

Modified Files
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doc/src/sgml/mvcc.sgml | 47 +++++++++++++++++++++++++++--------------------
1 file changed, 27 insertions(+), 20 deletions(-)