[Doc] Added 'See also' to split on str.join() (and vice-versa)

Author: adorilson

Doc/library/stdtypes.rst

@@ -2202,6 +2202,8 @@ expression support in the :mod:`re` module).
       >>> '-'.join('Python')
       'P-y-t-h-o-n'
 
+   See also :meth:`split`.
+
 
 .. method:: str.ljust(width, fillchar=' ', /)
 
@@ -2414,6 +2416,8 @@ expression support in the :mod:`re` module).
       >>> "   foo   ".split(maxsplit=0)
       ['foo   ']
 
+   See also :meth:`join`.
+
 
 .. index::
    single: universal newlines; str.splitlines method