docs: express forbidden_remote_server_names as valid regex

this field expects a regex not a glob, so the correct value should be
".*" if one wants to block all remote server names. otherwise, setting
"*" as documented results in an error on start because the configuration
could not be properly parsed.

conduwuit-example.toml

@@ -1325,7 +1325,7 @@
 # sender user's server name, inbound federation X-Matrix origin, and
 # outbound federation handler.
 #
-# You can set this to ["*"] to block all servers by default, and then
+# You can set this to [".*"] to block all servers by default, and then
 # use `allowed_remote_server_names` to allow only specific servers.
 #
 # example: ["badserver\\.tld$", "badphrase", "19dollarfortnitecards"]

src/core/config/mod.rs

@@ -1525,7 +1525,7 @@ pub struct Config {
 	/// sender user's server name, inbound federation X-Matrix origin, and
 	/// outbound federation handler.
 	///
-	/// You can set this to ["*"] to block all servers by default, and then
+	/// You can set this to [".*"] to block all servers by default, and then
 	/// use `allowed_remote_server_names` to allow only specific servers.
 	///
 	/// example: ["badserver\\.tld$", "badphrase", "19dollarfortnitecards"]