Add missing version information in the ModuleApi (#13947)

Author: babolivier

changelog.d/13947.feature

@@ -0,0 +1 @@
+Add cache invalidation across workers to module API.

synapse/module_api/__init__.py

@@ -842,6 +842,8 @@ def register_cached_function(self, cached_func: CachedFunction) -> None:
         however invalidation that needs to go to other workers needs to call `invalidate_cache`
         on the module API instead.
 
+        Added in Synapse v1.69.0.
+
         Args:
             cached_function: The cached function that will be registered to receive invalidation
             locally and from other workers.
@@ -856,6 +858,8 @@ async def invalidate_cache(
         """Invalidate a cache entry of a cached function across workers. The cached function
         needs to be registered on all workers first with `register_cached_function`.
 
+        Added in Synapse v1.69.0.
+
         Args:
             cached_function: The cached function that needs an invalidation
             keys: keys of the entry to invalidate, usually matching the arguments of the