DOC: Series.count remove mention of "level" (pandas-dev#54526)

* DOC: Series.count remove mention of "level"

* leave return type as-is

Author: lukemanley

pandas/core/series.py

@@ -2150,7 +2150,7 @@ def count(self):
 
         Returns
         -------
-        int or Series (if level specified)
+        int
             Number of non-null values in the Series.
 
         See Also