DOC: Adding example and See also to head and tail method (#16416)

Author: Cheukting

pandas/core/generic.py

@@ -3582,7 +3582,7 @@ def head(self, n=5):
         5  parrot
         6   shark
 
-        Viewing the first 5 lines (the default)
+        Viewing the first 5 lines
         >>> df.head()
            animal
         0    bear
@@ -3633,7 +3633,7 @@ def tail(self, n=5):
         5  parrot
         6   shark
 
-        Viewing the last 5 lines (the default)
+        Viewing the last 5 lines
         >>> df.tail()
            animal
         2  falcon