Add a reminder to update comps

Unfortunately, comps do not support virtual provides,
so they need to be updated whenever main pypy3 changes.

pypy3.9.spec

@@ -65,6 +65,12 @@ URL:            http://pypy.org/
 %global goal_dir pypy/goal
 
 %if 0%{?fedora} >= 36
+# REMINDER: When updating the main pypy3 version for a certain Fedora release
+# make sure to update the python-classroom group in https://pagure.io/fedora-comps/
+#   1. locate comps-fXX.xml.in for each affected Fedora release
+#   2. inside the <id>python-classroom</id> group locate <packagereq ...>pypy3.N-devel</packagereq>
+#   3. change the package name to match the new version
+#   4. submit changes as a pull request and make sure somebody merges it
 %bcond_without main_pypy3
 %else
 %bcond_with main_pypy3