Move most /contrib README files into SGML. Some still need conversion

or will never be converted.

contrib/chkpass/README.chkpass

@@ -1,56 +0,0 @@
-$PostgreSQL: pgsql/contrib/chkpass/README.chkpass,v 1.5 2007/10/01 19:06:48 darcy Exp $
-
-Chkpass is a password type that is automatically checked and converted upon
-entry.  It is stored encrypted.  To compare, simply compare against a clear
-text password and the comparison function will encrypt it before comparing.
-It also returns an error if the code determines that the password is easily
-crackable.  This is currently a stub that does nothing.
-
-I haven't worried about making this type indexable.  I doubt that anyone
-would ever need to sort a file in order of encrypted password.
-
-If you precede the string with a colon, the encryption and checking are
-skipped so that you can enter existing passwords into the field.
-
-On output, a colon is prepended.  This makes it possible to dump and reload
-passwords without re-encrypting them.  If you want the password (encrypted)
-without the colon then use the raw() function.  This allows you to use the
-type with things like Apache's Auth_PostgreSQL module.
-
-The encryption uses the standard Unix function crypt(), and so it suffers
-from all the usual limitations of that function; notably that only the
-first eight characters of a password are considered.
-
-Here is some sample usage:
-
-test=# create table test (p chkpass);
-CREATE TABLE
-test=# insert into test values ('hello');
-INSERT 0 1
-test=# select * from test;
-       p
-----------------
- :dVGkpXdOrE3ko
-(1 row)
-
-test=# select raw(p) from test;
-      raw
----------------
- dVGkpXdOrE3ko
-(1 row)
-
-test=# select p = 'hello' from test;
- ?column?
-----------
- t
-(1 row)
-
-test=# select p = 'goodbye' from test;
- ?column?
-----------
- f
-(1 row)
-
-D'Arcy J.M. Cain
-darcy@druid.net
-