Edit docs/configuring-dns.md: clarify user ID shortness

This commit intends to clarify what "short user ID" means by comparing it with ":matrix.example.com"

Signed-off-by: Suguru Hirahara <acioustick@noreply.codeberg.org>

docs/configuring-dns.md

@@ -6,7 +6,7 @@ To set up Matrix on your domain, you'd need to do some DNS configuration.
 
 ## DNS setting for server delegation (optional)
 
-In the sample `vars.yml` ([`examples/vars.yml`](../examples/vars.yml)), we recommend to use a short user ID like `@alice:example.com`.
+In the sample `vars.yml` ([`examples/vars.yml`](../examples/vars.yml)), we recommend to use a short user ID like `@alice:example.com` instead of `@alice:matrix.example.com`.
 
 To use such an ID, you don't need to install anything on the actual `example.com` server. Instead, you need to instruct the Matrix network that Matrix services for `example.com` are redirected over to `matrix.example.com`. This redirection is also known as "delegation".
 

docs/configuring-playbook-federation.md

@@ -2,7 +2,7 @@
 
 By default, your server federates with the whole Matrix network. That is, people on your server can communicate with people on any other Matrix server.
 
-**Note**: in the sample `vars.yml` ([`examples/vars.yml`](../examples/vars.yml)), we recommend to use a short user ID like `@alice:example.com` and set up [server delegation](howto-server-delegation.md) / redirection. Without a proper configuration, your server will effectively not be part of the Matrix network. If you find your server is not federated, make sure to [check whether services work](maintenance-checking-services.md) and your server is properly delegated.
+**Note**: in the sample `vars.yml` ([`examples/vars.yml`](../examples/vars.yml)), we recommend to use a short user ID like `@alice:example.com` instead of `@alice:matrix.example.com` and set up [server delegation](howto-server-delegation.md) / redirection. Without a proper configuration, your server will effectively not be part of the Matrix network. If you find your server is not federated, make sure to [check whether services work](maintenance-checking-services.md) and your server is properly delegated.
 
 ## Federating only with select servers
 

docs/configuring-well-known.md

@@ -16,7 +16,7 @@ There are 3 types of well-known service discovery mechanism that Matrix makes us
 
 All services created by this playbook are meant to be installed on their own server (such as `matrix.example.com`), instead of the base domain (`example.com`).
 
-As [per the Server-Server specification](https://matrix.org/docs/spec/server_server/r0.1.0.html#server-discovery), to use a short Matrix user ID like `@alice:example.com` while hosting services on a subdomain such as `matrix.example.com`, the Matrix network needs to be instructed of [server delegation](howto-server-delegation.md) / redirection.
+As [per the Server-Server specification](https://matrix.org/docs/spec/server_server/r0.1.0.html#server-discovery), in order to use a short Matrix user ID like `@alice:example.com` instead of `@alice:matrix.example.com` while hosting services on a subdomain such as `matrix.example.com`, the Matrix network needs to be instructed of [server delegation](howto-server-delegation.md) / redirection.
 
 For simplicity reasons, this playbook recommends you to set up server delegation via a `/.well-known/matrix/server` file.