linkify changelog

Author: richvdh

CHANGES.md

@@ -8,7 +8,7 @@ Bugfixes
 - Do not expose the experimental `uk.half-shot.msc2778.login.application_service` flow in the login API, which caused a compatibility problem with Element iOS. ([\#8440](https://github.com/matrix-org/synapse/issues/8440))
 - Fix malformed log line in new federation "catch up" logic. ([\#8442](https://github.com/matrix-org/synapse/issues/8442))
 - Convert additional templates from inline HTML to Jinja2 templates. ([\#8444](https://github.com/matrix-org/synapse/issues/8444))
-- Fix DB query on startup for negative streams which caused long start up times. Introduced in #8374. ([\#8447](https://github.com/matrix-org/synapse/issues/8447))
+- Fix DB query on startup for negative streams which caused long start up times. Introduced in [\#8374](https://github.com/matrix-org/synapse/issues/8374). ([\#8447](https://github.com/matrix-org/synapse/issues/8447))
 
 
 Synapse 1.21.0rc1 (2020-10-01)