Add hyperlinks to the docs of some os.path functions (issue #16552).

Doc/library/os.path.rst

@@ -43,13 +43,15 @@ applications should use string objects to access all files.
 .. function:: abspath(path)
 
    Return a normalized absolutized version of the pathname *path*. On most
-   platforms, this is equivalent to ``normpath(join(os.getcwd(), path))``.
+   platforms, this is equivalent to calling the function :func:`normpath` as
+   follows: ``normpath(join(os.getcwd(), path))``.
 
 
 .. function:: basename(path)
 
-   Return the base name of pathname *path*.  This is the second half of the pair
-   returned by ``split(path)``.  Note that the result of this function is different
+   Return the base name of pathname *path*.  This is the second element of the
+   pair returned by passing *path* to the function :func:`split`.  Note that
+   the result of this function is different
    from the Unix :program:`basename` program; where :program:`basename` for
    ``'/foo/bar/'`` returns ``'bar'``, the :func:`basename` function returns an
    empty string (``''``).
@@ -64,8 +66,8 @@ applications should use string objects to access all files.
 
 .. function:: dirname(path)
 
-   Return the directory name of pathname *path*.  This is the first half of the
-   pair returned by ``split(path)``.
+   Return the directory name of pathname *path*.  This is the first element of
+   the pair returned by passing *path* to the function :func:`split`.
 
 
 .. function:: exists(path)
@@ -276,7 +278,8 @@ applications should use string objects to access all files.
    *path* is empty, both *head* and *tail* are empty.  Trailing slashes are
    stripped from *head* unless it is the root (one or more slashes only).  In
    all cases, ``join(head, tail)`` returns a path to the same location as *path*
-   (but the strings may differ).
+   (but the strings may differ).  Also see the functions :func:`dirname` and
+   :func:`basename`.
 
 
 .. function:: splitdrive(path)