proc.c: fix rdoc for Method class documentation

* proc.c: [DOC] fix rdoc syntax for the class documentation of
  the Method class so that it is displayed in the rendered docs.

git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/trunk@60620 b2dd03c8-39d4-4d8f-98ff-823fe69b080e

proc.c

@@ -1470,7 +1470,7 @@ method_entry_defined_class(const rb_method_entry_t *me)
 
 /**********************************************************************
  *
- * Document-class : Method
+ * Document-class: Method
  *
  *  Method objects are created by <code>Object#method</code>, and are
  *  associated with a particular object (not just with a class). They