docs: use correct changlog fragment extension

Part-of: <https://dev.funkwhale.audio/funkwhale/funkwhale/-/merge_requests/2318>
2023-01-18 14:59:20 +01:00 · 2023-01-18 14:59:20 +01:00 · ee07023282
commit ee07023282
--- a/changes/changelog.d/compose.update
+++ b/changes/changelog.d/compose.update