Add documentation for --with-greenplum, and reformat README with mark…

…down

README.markdown

@@ -0,0 +1,111 @@
+PL/ruby
+=======
+
+  PL/Ruby is a loadable procedural language for the PostgreSQL database
+  system that enables the Ruby language to create functions and trigger
+  procedures.
+
+
+Prerequisite
+------------
+
+> * ruby 1.8.7 or later (maybe 1.8.6 too)
+> * postgresql >= 7.3
+
+  All PostgreSQL headers need to be installed. Command (see `INSTALL` in the
+  directory postgresql-7.x.y)
+
+        make install-all-headers 
+
+Installation
+------------
+
+        ruby extconf.rb
+        make
+        make install
+
+  You may need to specify :
+
+        --with-pg-config=<location of the pg_config command of PostgreSQL>
+
+        --disable-conversion
+  by default plruby try to convert a postgres type to a ruby class
+  This option give the possibility to disable all conversions
+
+       --with-suffix=<suffix to add>
+
+  For example
+
+        ruby extconf.rb --with-suffix=_geo
+
+  will create `plruby_geo.so`
+
+        --with-greenplum
+  To build plruby for Greenplum istead of PostgreSQL 
+
+
+  *Example usage*
+
+        ruby extconf.rb --with-pg-config=/usr/local/bin/pg_config
+
+Test (and examples)
+-------------------
+
+  WARNING : if plruby was compiled without --disable-conversion
+  you must **FIRST** run `make install` before `make test`
+
+        make test
+
+  this will run the 2 commands :
+
+        ( cd test/plt; ./runtest )
+        ( cd test/plp; ./runtest )
+
+  The database `plruby_test` is created and then destroyed. Don't use it if 
+  such a database exist on your system.
+
+  Now create the PL/Ruby language in PostgreSQL
+
+  Since the `pg_language` system catalog is private to each database,
+  the new language can be created only for individual databases,
+  or in the template1 database. In the latter case, it is
+  automatically available in all newly created databases.
+
+  The commands to create the new language are:
+
+        create function plruby_call_handler () returns language_handler
+        as 'path-to-plruby-shared-lib'
+        language 'C';
+
+        create trusted language 'plruby'
+        handler plruby_call_handler
+        lancompiler 'PL/Ruby';
+
+
+  The `trusted` keyword on `create language` tells PostgreSQL,
+  that all users (not only those with superuser privilege) are
+  permitted to create functions with `LANGUAGE 'plruby'`. This is
+  absolutely safe, because there is nothing a normal user can do
+  with PL/Ruby, to get around access restrictions he/she has.
+
+Documentation
+-------------
+
+  see `plruby.rd` and `plruby.html`
+
+Development
+-----------
+
+  New releases and sources can be obtained from <http://github.com/knu/postgresql-plruby>
+
+Copying
+-------
+
+  This extension module is copyrighted free software by Guy Decoux.
+
+  You can redistribute it and/or modify it under the same term as Ruby.
+
+* * *
+
+Guy Decoux <ts@moulon.inra.fr> (original author, deceased in July 2008)   
+Akinori MUSHA <knu@idaemons.org> (current maintainer)