pgsql: doc: Clean up title case use

doc: Clean up title case use

Note: Following existing practice, titles of formalpara and step are
not titlecased.

Branch
------
master

Details
-------
https://git.postgresql.org/pg/commitdiff/8e929a4667a1f4f97c5447f54b8176b0ee15aa7d

Modified Files
--------------
doc/src/sgml/amcheck.sgml            |  6 +++---
doc/src/sgml/arch-dev.sgml           |  2 +-
doc/src/sgml/backup.sgml             |  7 ++++---
doc/src/sgml/charset.sgml            |  8 ++++----
doc/src/sgml/config.sgml             |  6 +++---
doc/src/sgml/custom-scan.sgml        |  2 +-
doc/src/sgml/dfunc.sgml              |  2 +-
doc/src/sgml/docguide.sgml           |  2 +-
doc/src/sgml/earthdistance.sgml      |  8 ++++----
doc/src/sgml/ecpg.sgml               |  2 +-
doc/src/sgml/extend.sgml             |  2 +-
doc/src/sgml/fdwhandler.sgml         | 16 ++++++++--------
doc/src/sgml/features.sgml           | 10 +++++-----
doc/src/sgml/func.sgml               | 14 +++++++-------
doc/src/sgml/gist.sgml               |  2 +-
doc/src/sgml/high-availability.sgml  |  6 +++---
doc/src/sgml/install-windows.sgml    |  2 +-
doc/src/sgml/installation.sgml       |  4 ++--
doc/src/sgml/intro.sgml              |  2 +-
doc/src/sgml/jit.sgml                |  2 +-
doc/src/sgml/json.sgml               |  4 ++--
doc/src/sgml/libpq.sgml              |  2 +-
doc/src/sgml/limits.sgml             |  2 +-
doc/src/sgml/lobj.sgml               |  4 ++--
doc/src/sgml/maintenance.sgml        |  2 +-
doc/src/sgml/monitoring.sgml         |  6 +++---
doc/src/sgml/mvcc.sgml               | 16 ++++++++--------
doc/src/sgml/nls.sgml                |  2 +-
doc/src/sgml/pageinspect.sgml        |  2 +-
doc/src/sgml/perform.sgml            |  4 ++--
doc/src/sgml/planstats.sgml          |  2 +-
doc/src/sgml/plhandler.sgml          |  2 +-
doc/src/sgml/plpgsql.sgml            | 26 +++++++++++++-------------
doc/src/sgml/plpython.sgml           |  2 +-
doc/src/sgml/protocol.sgml           |  2 +-
doc/src/sgml/ref/create_table.sgml   |  4 ++--
doc/src/sgml/ref/pg_rewind.sgml      |  2 +-
doc/src/sgml/ref/pgbench.sgml        |  6 +++---
doc/src/sgml/ref/pgtesttiming.sgml   |  8 ++++----
doc/src/sgml/ref/pgupgrade.sgml      |  4 ++--
doc/src/sgml/ref/postgres-ref.sgml   |  2 +-
doc/src/sgml/runtime.sgml            |  2 +-
doc/src/sgml/sourcerepo.sgml         |  2 +-
doc/src/sgml/spgist.sgml             |  2 +-
doc/src/sgml/storage.sgml            |  4 ++--
doc/src/sgml/syntax.sgml             |  6 +++---
doc/src/sgml/tablesample-method.sgml |  2 +-
doc/src/sgml/xaggr.sgml              |  2 +-
doc/src/sgml/xfunc.sgml              |  6 +++---
doc/src/sgml/xindex.sgml             |  6 +++---
doc/src/sgml/xoper.sgml              |  2 +-
doc/src/sgml/xtypes.sgml             |  2 +-
52 files changed, 123 insertions(+), 122 deletions(-)