Update docs for mautrix bridges: remove redundant descriptions

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

docs/configuring-playbook-bridge-appservice-kakaotalk.md

@@ -24,9 +24,7 @@ To enable the bridge, add the following configuration to your `inventory/host_va
 matrix_appservice_kakaotalk_enabled: true
 ```
 
-You may optionally wish to add some [Additional configuration](#additional-configuration), or to [prepare for double-puppeting](#set-up-double-puppeting) before the initial installation.
-
-### Additional configuration
+### Extending the configuration
 
 There are some additional things you may wish to configure about the bridge.
 

docs/configuring-playbook-bridge-mautrix-discord.md

@@ -30,8 +30,6 @@ To enable the bridge, add the following configuration to your `inventory/host_va
 matrix_mautrix_discord_enabled: true
 ```
 
-You may optionally wish to add some [Additional configuration](#additional-configuration), or to [prepare for double-puppeting](#set-up-double-puppeting) before the initial installation.
-
 ### Extending the configuration
 
 There are some additional things you may wish to configure about the bridge.

docs/configuring-playbook-bridge-mautrix-slack.md

@@ -30,8 +30,6 @@ To enable the bridge, add the following configuration to your `inventory/host_va
 matrix_mautrix_slack_enabled: true
 ```
 
-You may optionally wish to add some [Additional configuration](#additional-configuration), or to [prepare for double-puppeting](#set-up-double-puppeting) before the initial installation.
-
 ### Extending the configuration
 
 There are some additional things you may wish to configure about the bridge.