pgsql: revert: add transaction processing chapter with internals info

revert:  add transaction processing chapter with internals info

This doc patch (master hash 66bc9d2d3e) was decided to be too
significant for backpatching, so reverted in all but master.  Also fix
SGML file header comment in master.

Reported-by:    Peter Eisentraut

Discussion: https://postgr.es/m/c6304b19-6ff7-f3af-0148-cf7aa7e2fbfd@enterprisedb.com

Backpatch-through: 11

Branch
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REL_14_STABLE

Details
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https://git.postgresql.org/pg/commitdiff/cf9bcb0f0421af15d7b9bebe00c8cf649bee399d

Modified Files
--------------
doc/src/sgml/catalogs.sgml              |   7 +-
doc/src/sgml/config.sgml                |   6 +-
doc/src/sgml/datatype.sgml              |   3 +-
doc/src/sgml/filelist.sgml              |   1 -
doc/src/sgml/func.sgml                  |  20 +---
doc/src/sgml/glossary.sgml              |   3 +-
doc/src/sgml/monitoring.sgml            |   6 +-
doc/src/sgml/pgrowlocks.sgml            |   3 +-
doc/src/sgml/postgres.sgml              |   1 -
doc/src/sgml/ref/release_savepoint.sgml |  62 ++++------
doc/src/sgml/ref/rollback.sgml          |   8 +-
doc/src/sgml/ref/rollback_to.sgml       |   5 +-
doc/src/sgml/wal.sgml                   |   6 +-
doc/src/sgml/xact.sgml                  | 205 --------------------------------
14 files changed, 44 insertions(+), 292 deletions(-)