pgsql: meson: docs: Allow configuring simple/website style

meson: docs: Allow configuring simple/website style

The meson docs generation hardcoded using the website style so far. Make it
configurable via a meson option.

Reviewed-by: Justin Pryzby <pryzby@telsasoft.com>
Reported-by: Peter Eisentraut <peter.eisentraut@enterprisedb.com>
Discussion: https://postgr.es/m/3fc3bb9b-f7f8-d442-35c1-ec82280c564a@enterprisedb.com

Branch
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master

Details
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https://git.postgresql.org/pg/commitdiff/9d2a464a04846961ffa6b5f2c25b68bc2bf0af67

Modified Files
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doc/src/sgml/installation.sgml | 12 ++++++++++++
doc/src/sgml/meson.build       |  7 ++++---
meson_options.txt              |  3 +++
3 files changed, 19 insertions(+), 3 deletions(-)