PEP 615: Fix incorrect RFC link (#2662)

Author: aphedges

pep-0615.rst

@@ -55,7 +55,7 @@ time zone database (also called the "tz" database or the Olson database
 distributed — it is present by default on many Unix-like operating systems.
 Great care goes into the stability of the database: there are IETF RFCs both
 for the maintenance procedures (:rfc:`6557`) and for the compiled
-binary (TZif) format (:rfc:`8636`).  As such, it is likely that adding
+binary (TZif) format (:rfc:`8536`).  As such, it is likely that adding
 support for the compiled outputs of the IANA database will add great value to
 end users even with the relatively long cadence of standard library releases.