New and updated example documentation

[David Blevins]

Been doing some work on the documentation for the examples.  Many of  
them were pretty bare-bones and in some cases, non-existent.  Been on  
the TODO list for quite some time, but finally got some time post- 
release to get these taken care of.  I urge everyone to give them a  
look over.

New example documentation:
  http://openejb.apache.org/3.0/ejb-21-compatibility-example.html
  http://openejb.apache.org/3.0/custom-injection.html
  http://openejb.apache.org/3.0/injection-of-entitymanager-example.html
  http://openejb.apache.org/3.0/testing-transactions-example.html
  http://openejb.apache.org/3.0/testing-security-example.html

Updated/rewritten example documentation:

  http://openejb.apache.org/3.0/simple-stateless-example.html
  http://openejb.apache.org/3.0/simple-stateful-example.html
  http://openejb.apache.org/3.0/injection-of-env-entry-example.html
  http://openejb.apache.org/3.0/injection-of-other-ejbs-example.html
  http://openejb.apache.org/3.0/injection-of-datasource-example.html

-David