address review: link to imath

Author: skirpichev

peps/pep-0791.rst

@@ -110,7 +110,7 @@ The chosen name seems consistent with one existing domain-specific mathematical
 
 We should note, that the `Imath
 <https://github.com/AcademySoftwareFoundation/Imath>`_ C++ library includes
-Python bindings with the same name.  There is also an ``imath`` project on
+Python bindings with the same name.  There is also an :pypi:`imath` project on
 PyPI, but only with two releases, with the most recent one four years ago.  Its
 repository is no longer accessible.