Inconsistencies in documentation of row-level locking

Hi all,

Currently all the row-level lock modes are described in the page for
SELECT query:
http://www.postgresql.org/docs/devel/static/explicit-locking.html#LOCKING-ROWS
However, after browsing the documentation, I noticed in the page
describing all the explicit locks of the system that there is a
portion dedicated to row-level locks and this section is not
mentioning at all FOR KEY SHARE and FOR NO KEY UPDATE. It seems that
this is something rather misleading for the user:
http://www.postgresql.org/docs/devel/static/explicit-locking.html#LOCKING-ROWS

Attached is a patch that refactors the whole and improves the documentation:
- Addition of a table showing the conflicts between each lock
- Moved description of each row-level lock mode to the explicit locking page
- Addition of a link in SELECT portion to redirect the user to the
explicit locking page
Regards,
--
Michael