Fix typo in federation_verify_certificates in config documentation. (#15139)

changelog.d/15139.doc

+Correct reference to `federation_verify_certificates` in configuration documentation.

docs/usage/configuration/config_documentation.md

@@ -1105,7 +1105,7 @@ This setting should only be used in very specific cases, such as
 federation over Tor hidden services and similar. For private networks
 of homeservers, you likely want to use a private CA instead.
 
-Only effective if `federation_verify_certicates` is `true`.
+Only effective if `federation_verify_certificates` is `true`.
 
 Example configuration:
 ```yaml