docs: Fix a linx in OEP-50

Link to the correct hooks documentation in the edx-platform repo.  That
doc could be much improved but at least now we won't have a dead link.

oeps/architectural-decisions/oep-0050-hooks-extension-framework.rst

@@ -37,7 +37,7 @@ Motivation
 **********
 
 Following the open-closed principle, it would be desirable for the open edX
-project to allow the extension points (great `summary of the current options`_)
+project to allow the extension points (great :doc:`summary of the current options<edx-platform:hooks/index>`)
 to modify as much of the code paths that define the business rules of an
 open edX instance in a way that is consistent and repeatable.
 
@@ -56,9 +56,6 @@ This proposal draws inspiration from the cumulative experience of eduNEXT as the
 lead author, other members of the community, and from one of the largest
 extendable platforms for the web today for many years already, WordPress.
 
-.. _summary of the current options: https://github.com/openedx/edx-platform/blob/master/docs/guides/extension_points.rst
-
-
 Specification
 *************
 

oeps/conf.py

@@ -14,6 +14,7 @@
 
 import sys
 import os
+import re
 
 from datetime import datetime
 
@@ -337,12 +338,24 @@
 #texinfo_no_detailmenu = False
 
 
+# Intersphinx Extension Configuration
+DIGITS_ONLY = r"^\d+$"
+rtd_language = os.environ.get("READTHEDOCS_LANGUAGE", "en")
+rtd_version = os.environ.get("READTHEDOCS_VERSION", "latest")
+if re.search(DIGITS_ONLY, rtd_version):
+    # This is a PR build, use the latest versions of the other repos.
+    rtd_version = "latest"
+
 # Example configuration for intersphinx: refer to the Python standard library.
 intersphinx_mapping = {
     "python": (
         'https://docs.python.org/',
         None
     ),
+    "edx-platform": (
+        f"https://docs.openedx.org/projects/edx-platform/{rtd_language}/{rtd_version}",
+        None,
+    ),
 }
 
 # -- Read the Docs Specific Configuration