Merge branch 'master' into develop

Author: David Robertson

changelog.d/13333.doc

@@ -0,0 +1 @@
+Document the new `rc_invites.per_issuer` throttling option added in Synapse 1.63.

docs/usage/configuration/config_documentation.md

@@ -1528,6 +1528,8 @@ The `rc_invites.per_user` limit applies to the *receiver* of the invite, rather
 sender, meaning that a `rc_invite.per_user.burst_count` of 5 mandates that a single user
 cannot *receive* more than a burst of 5 invites at a time.
 
+In contrast, the `rc_invites.per_issuer` limit applies to the *issuer* of the invite, meaning that a `rc_invite.per_issuer.burst_count` of 5 mandates that single user cannot *send* more than a burst of 5 invites at a time.
+
 Example configuration:
 ```yaml
 rc_invites:
@@ -1537,7 +1539,13 @@ rc_invites:
   per_user:
     per_second: 0.004
     burst_count: 3
+  per_issuer:
+    per_second: 0.5
+    burst_count: 5
 ```
+
+_Changed in version 1.63:_ added the `per_issuer` limit.
+
 ---
 ### `rc_third_party_invite`