pgsql: doc: Make HTML ids discoverable

doc: Make HTML ids discoverable

In the HTML output, this decorates section headers and variable list
terms with a marker ("#") that is a link to the same section/term.
That way, links inside a page can be discovered for easier sharing.
The marker only appears when hovering.

This now requires that all elements that are candidates for such a
link have an id attribute. Otherwise, an error will be generated.
All previously missing ids have been added prior to this patch.

Author: Brar Piening <brar(at)gmx(dot)de>
Reviewed-by: Karl O. Pinc <kop(at)karlpinc(dot)com>
Discussion: https://www.postgresql.org/message-id/flat/CAB8KJ=jpuQU9QJe4+RgWENrK5g9jhoysMw2nvTN_esoOU0=a_w(at)mail(dot)gmail(dot)com

Branch
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master

Details
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https://git.postgresql.org/pg/commitdiff/e2922702a3027945f139f9b0c7b4686423304e21

Modified Files
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doc/src/sgml/stylesheet-html-common.xsl | 127 ++++++++++++++++++++++++++++++++
doc/src/sgml/stylesheet.css | 11 +++
2 files changed, 138 insertions(+)