pgsql: doc: Don't hide the "Up" link when it is the same as "Home"

doc: Don't hide the "Up" link when it is the same as "Home"

The original stylesheets seemed to think this was a good idea, but our
users find it confusing and unhelpful, so undo that logic.

Reported-by: Fabien COELHO <coelho@cri.ensmp.fr>
Discussion: /messages/by-id/alpine.DEB.2.22.394.2006210914370.859381@pseudo

Branch
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REL_12_STABLE

Details
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https://git.postgresql.org/pg/commitdiff/6a8f6aee0cbea617df90fe3b715d6dd73e0f8c04

Modified Files
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doc/src/sgml/stylesheet.xsl | 163 ++++++++++++++++++++++++++++++++++++++++++--
1 file changed, 159 insertions(+), 4 deletions(-)