Added earlier link to Acquistion.

lib/Components/ExtensionClass/doc/ExtensionClass.stx

@@ -26,7 +26,7 @@ Extension Classes, Python Extension Types Become Classes
 
     - A protocol for accessing subobjects "in the context of" their
       containers.  This is used to implement custom method types
-      and environmental acquisition.
+      and "environmental acquisition":Acquisition.html.
 
     - A protocol for overriding method call semantics.  This is used
       to implement "synchonized" classes and could be used to