Update docs/README.md: create the "configuration options" section and add a note

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

docs/README.md

@@ -18,6 +18,33 @@ There are two installation guides available for beginners and advanced users.
 
     - [Installing](installing.md)
 
+## 🛠️ Configuration options
+
+<!--
+NOTE:
+- Avoid putting the same anchor links as configuring-playbook.md lists under the "configuration options" section. Note that most of them are linked to "configure-playbook-*.md" and their titles start with "Setting up" (e.g. "Setting up Hydrogen").
+-->
+
+You can check useful documentation for configuring components here: [Configuring the playbook](configuring-playbook.md)
+
+- [Administration](configuring-playbook.md#administration) -  services that help you in administrating and monitoring your Matrix installation
+
+- [Authentication and user-related](configuring-playbook.md#authentication-and-user-related) - extend and modify how users are authenticated on your homeserver
+
+- [Bots](configuring-playbook.md#bots) - bots provide various additional functionality to your installation
+
+- [Bridges](configuring-playbook.md#bridging-other-networks) - bridges can be used to connect your Matrix installation with third-party communication networks
+
+- [Clients](configuring-playbook.md#clients) - web clients for Matrix that you can host on your own domains
+
+- [Core service adjustments](configuring-playbook.md#core-service-adjustments) - backbone of your Matrix system
+
+- [File Storage](configuring-playbook.md#file-storage) - use alternative file storage to the default `media_store` folder
+
+<!-- NOTE: sort list items above alphabetically -->
+
+- [Other specialized services](configuring-playbook.md#other-specialized-services) - various services that don't fit any other categories
+
 ## 👨‍🔧 Maintenance
 
 If your server and services experience issues, feel free to come to [our support room](https://matrix.to/#/#matrix-docker-ansible-deploy:devture.com) and ask for help.