docs: updating docs according to PR comment

Author: seanjedi

pandas/core/groupby/groupby.py

@@ -417,7 +417,7 @@ class providing the base-class of operations.
     If a string is chosen, then it needs to be the string of the
     function you want to use.
 
-    IE: ``grouped.transform("sum")``.
+    IE: ``pd.%(klass)s = grouped.transform("sum")``.
 
     .. versionchanged:: 1.1.0
 *args