DOC: update the DataFrame.head() docstring (#20206)

Author: aterrel

Diff for: pandas/core/generic.py

@@ -3605,7 +3605,11 @@ def f(x):
 
     def head(self, n=5):
         """
-        Return the first n rows.
+        Return the first `n` rows.
+
+        This function returns the first `n` rows for the object based on the
+        underlying index. It is useful for quickly testing if your object
+        has the right type of data in it.
 
         Parameters
         ----------
@@ -3619,7 +3623,7 @@ def head(self, n=5):
 
         See Also
         --------
-        pandas.DataFrame.tail
+        pandas.DataFrame.tail: Returns the last `n` rows.
 
         Examples
         --------