Fix one more readthedocs Intersphinx URL

Author: chk1

letsencrypt-compatibility-test/docs/conf.py

@@ -309,6 +309,6 @@
     'python': ('https://docs.python.org/', None),
     'acme': ('https://acme-python.readthedocs.org/en/latest/', None),
     'letsencrypt': ('https://letsencrypt.readthedocs.org/en/latest/', None),
-    'letsencrypt-apache': ('https://letsencrypt-apache.readthedocs.org', None),
-    'letsencrypt-nginx': ('https://letsencrypt-nginx.readthedocs.org', None),
+    'letsencrypt-apache': ('https://letsencrypt-apache.readthedocs.org/en/latest/', None),
+    'letsencrypt-nginx': ('https://letsencrypt-nginx.readthedocs.org/en/latest/', None),
 }