Ignore date-rotated logs (#9018)

Ex.

 - homeserver.log.2020-12-29
 - homeserver.log.2020-12-31

.gitignore

@@ -16,6 +16,7 @@ _trial_temp*/
 # stuff that is likely to exist when you run a server locally
 /*.db
 /*.log
+/*.log.*
 /*.log.config
 /*.pid
 /.python-version

changelog.d/9018.misc

@@ -0,0 +1 @@
+Ignore date-rotated homeserver logs saved to disk.