Docs improvements

1) mvcc.sgml.patch
Update comments about installation of DocBook on FreeBSD. DocBook v4.2 is
present in ports now.

2) docguide.sgml.patch
Table of compatibility of table-lock modes. IMHO, it's useful, clear for
understanding. Text view of the table is:
| AS | RS | RE | SUE | S | SRE | E | AE |
----+-------+-------+-------+-------+-------+-------+-------+-------+
AS | O | O | O | O | O | O | O | X |
----+-------+-------+-------+-------+-------+-------+-------+-------+
RS | O | O | O | O | O | O | X | X |
----+-------+-------+-------+-------+-------+-------+-------+-------+
RE | O | O | O | O | X | X | X | X |
----+-------+-------+-------+-------+-------+-------+-------+-------+
SUE | O | O | O | X | X | X | X | X |
----+-------+-------+-------+-------+-------+-------+-------+-------+
S | O | O | X | X | O | X | X | X |
----+-------+-------+-------+-------+-------+-------+-------+-------+
SRE | O | O | X | X | X | X | X | X |
----+-------+-------+-------+-------+-------+-------+-------+-------+
E | O | X | X | X | X | X | X | X |
----+-------+-------+-------+-------+-------+-------+-------+-------+
AE | X | X | X | X | X | X | X | X |
----+-------+-------+-------+-------+-------+-------+-------+-------+

Upper row and left column contain abbreviation of lock modes by the first
characters( AS - ACCESS SHARE )
--
Teodor Sigaev E-mail: teodor(at)sigaev(dot)ru
WWW: http://www.sigaev.ru/