[3.6] bpo-26656: Improve re.compile documentation (GH-3211) (GH-3225)

- Link to the regular expressions object documentation - Clarify that it can be used with more than the two methods currently stated. (cherry picked from commit ed94a8b)

Author: Mariatta

Doc/library/re.rst

@@ -490,9 +490,10 @@ form.
 
 .. function:: compile(pattern, flags=0)
 
- Compile a regular expression pattern into a regular expression object, which
- can be used for matching using its :func:`~regex.match` and
- :func:`~regex.search` methods, described below.
+ Compile a regular expression pattern into a :ref:`regular expression object
+ <re-objects>`, which can be used for matching using its
+ :func:`~regex.match`, :func:`~regex.search` and other methods, described
+ below.
 
  The expression's behaviour can be modified by specifying a *flags* value.
  Values can be any of the following variables, combined using bitwise OR (the