DOC: core/generic/drop doc-string change

Author: jreback

pandas/core/generic.py

@@ -1092,7 +1092,7 @@ def drop(self, labels, axis=0, level=None):
 
         Parameters
         ----------
-        labels : list-like; passing a string or tuple will be treated as a single index label
+        labels : single label or list-like
         axis : int
         level : int or name, default None
             For MultiIndex