Added a note that stdlib no longer ships with PE 3.7+

Users didn't realize we stopped shipping stdlib module with PE. I added this information to the stdlib readme.

Author: jbondpdx

README.markdown

@@ -27,6 +27,8 @@ modules. Puppet modules make heavy use of this standard library. The stdlib modu
  * Defined resource types
  * Types
  * Providers
+ 
+> *Note:* As of version 3.7, Puppet Enterprise no longer includes the stdlib module. If you're running Puppet Enterprise, you should install the most recent release of stdlib for compatibility with Puppet modules.
 
 ##Setup
 
@@ -676,6 +678,8 @@ of the regular expressions match the string passed in, compilation aborts with a
 
 ##Limitations
 
+As of Puppet Enterprise version 3.7, the stdlib module is no longer included in PE. PE users should install the most recent release of stdlib for compatibility with Puppet modules.
+
 ###Version Compatibility
 
 Versions | Puppet 2.6 | Puppet 2.7 | Puppet 3.x | Puppet 4.x |