Merge pull request #2822 from rgieseke/patch-3

DOC: Fix typos

Author: y-p

pandas/core/groupby.py

@@ -25,7 +25,7 @@
 arg : function or dict
     Function to use for aggregating groups. If a function, must either
     work when passed a DataFrame or when passed to DataFrame.apply. If
-    pass a dict, the keys must be DataFrame column names
+    passed a dict, the keys must be DataFrame column names.
 
 Notes
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