pgsql: Doc: tweak v18 to avoid "exceed the available area" PDF problems

Doc: tweak v18 to avoid "exceed the available area" PDF problems.

It's quite unclear to me why these two examples are overrunning the
right margin in the v18 docs, when the identical examples are fine in
other branches. Nonetheless, the buildfarm (member alabio) is showing
the same results I see locally, so it's real, and I lack the time
right now to dig any deeper. Throw a &zwsp into one example to allow
a line break, and adjust the sample UUID in the other one so that FOP
thinks it's a breakable word.

Branch
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REL_18_STABLE

Details
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https://git.postgresql.org/pg/commitdiff/de2793682d98e8fe458f192b1a0e48e9fd623b40

Modified Files
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doc/src/sgml/datatype.sgml | 2 +-
doc/src/sgml/func.sgml | 2 +-
2 files changed, 2 insertions(+), 2 deletions(-)