pgsql: doc: Fix link to FreeBSD documentation project

doc: Fix link to FreeBSD documentation project

The FreeBSD site was changed with a redirect, which in turn seems to
lead to a 404. Replace with the working link.

Author: James Coleman <jtc331@gmail.com>
Discussion: https://postgr.es/m/CAAaqYe_JZRj+KPn=hACtwsg1iLRYs=jYvxG1NW4AnDeUL1GD-Q@mail.gmail.com

Branch
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REL_14_STABLE

Details
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https://git.postgresql.org/pg/commitdiff/293a6ac4b9898febe1cf9a4614facf6128be5d77

Modified Files
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doc/src/sgml/docguide.sgml | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)