pgsql: doc: Fix DocBook XML validity

doc: Fix DocBook XML validity

The main problem is that DocBook SGML allows indexterm elements just
about everywhere, but DocBook XML is stricter.  For example, this common
pattern

    <varlistentry>
     <indexterm>...</indexterm>
     <term>...</term>
     ...
    </varlistentry>

needs to be changed to something like

    <varlistentry>
     <term>...<indexterm>...</indexterm></term>
     ...
    </varlistentry>

See also bb4eefe7bf518e42c73797ea37b033a5d8a8e70a.

There is currently nothing in the build system that enforces that things
stay valid, because that requires additional tools and will receive
separate consideration.

Branch
------
master

Details
-------
http://git.postgresql.org/pg/commitdiff/3a9d430af515e9dd8a9d34a4011367e667a66521

Modified Files
--------------
doc/src/sgml/auth-delay.sgml         |    6 +-
doc/src/sgml/auto-explain.sgml       |   48 +--
doc/src/sgml/config.sgml             |  733 ++++++++++++++++++++++------------
doc/src/sgml/dfunc.sgml              |   56 ++-
doc/src/sgml/installation.sgml       |    7 +-
doc/src/sgml/libpq.sgml              |    4 +-
doc/src/sgml/logicaldecoding.sgml    |    2 +-
doc/src/sgml/pageinspect.sgml        |   42 +-
doc/src/sgml/pgfreespacemap.sgml     |    6 +-
doc/src/sgml/pgstatstatements.sgml   |   16 +-
doc/src/sgml/pgstattuple.sgml        |    7 +-
doc/src/sgml/plperl.sgml             |  278 +++++++------
doc/src/sgml/pltcl.sgml              |   23 +-
doc/src/sgml/protocol.sgml           |    3 +-
doc/src/sgml/queries.sgml            |   16 +-
doc/src/sgml/recovery-config.sgml    |   55 +--
doc/src/sgml/ref/alter_table.sgml    |   13 +-
doc/src/sgml/ref/pg_recvlogical.sgml |    8 +-
doc/src/sgml/ref/psql-ref.sgml       |   24 +-
doc/src/sgml/rules.sgml              |    4 +-
doc/src/sgml/runtime.sgml            |   30 +-
doc/src/sgml/sepgsql.sgml            |   20 +-
doc/src/sgml/sslinfo.sgml            |   54 +--
doc/src/sgml/textsearch.sgml         |   26 +-
24 files changed, 903 insertions(+), 578 deletions(-)