Add removeprefix() and removesuffix() to the str method summary.

The "Text and Binary Sequence Type Methods Summary" section did not include the `removeprefix` and `removesuffix` functions, which were present later on in the "String Methods" section and the "Bytes and Bytearray Operations" section

This is a small change that rectifies that.

Author: darida12321

Doc/library/stdtypes.rst

@@ -1662,6 +1662,10 @@ category.
 |                          |  :meth:`str.startswith`                   |  :meth:`bytes.startswith`                         |
 |                          +-------------------------------------------+---------------------------------------------------+
 |                          |  :meth:`str.endswith`                     |  :meth:`bytes.endswith`                           |
+|                          +------------------+------------------------+--------------------+------------------------------+
+|                          |  :meth:`str.removeprefix`                 |  :meth:`bytes.removeprefix`                       |
+|                          +-------------------------------------------+---------------------------------------------------+
+|                          |  :meth:`str.removesuffix`                 |  :meth:`bytes.removesuffix`                       |
 |                          +-------------------------------------------+---------------------------------------------------+
 |                          |  :meth:`str.count`                        |  :meth:`bytes.count`                              |
 |                          +-------------------------------------------+---------------------------------------------------+