Update MSC number.

Author: clokep

…event-propery-contains-push-condition.md …event-propery-contains-push-condition.mdproposals/xxxx-exact-event-propery-contains-push-condition.md renamed to proposals/3966-exact-event-propery-contains-push-condition.md proposals/xxxx-exact-event-propery-contains-push-condition.md renamed to proposals/3966-exact-event-propery-contains-push-condition.md

@@ -1,4 +1,4 @@
-# MSC0000: `exact_event_property_contains` push rule condition
+# MSC3966: `exact_event_property_contains` push rule condition
 
 [MSC3952](https://github.com/matrix-org/matrix-spec-proposals/pull/3952):
 Intentional mentions requires a way for a push rule condition to search
@@ -56,7 +56,7 @@ for *exact* matches.
 
 ## Unstable prefix
 
-During development `org.matrix.msc0000.exact_event_property_contains` shall be
+During development `org.matrix.msc3966.exact_event_property_contains` shall be
 used in place of `exact_event_property_contains`.
 
 ## Dependencies