Add a note about cases to create multiple accounts/users

Since one of the quick start guide's goals is to set up an own user account, this commit adds the note about creating multiple accounts/users to installing.md and registering-users.md only. It should be fine as registering-users.md is linked from quick-start.md

Also:
- On installing.md and quick-start.md, change instruction from what encourages to select "admin=yes" or "admin=no" to what encourages to use "admin=yes", since your user account will be the sole user on the server, as long as you set up the server by following the documentation
- Remove the link to registering-users.md from quick-start.md as the documentation is already linked above, under the header of the section
- Sync docs/installing.md with other documentation

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

docs/installing.md

@@ -80,16 +80,18 @@ After creating the user account, you can log in to it with [Element Web](configu
 To create your user account via this Ansible playbook, run the command below on your local computer.
 
 **Notes**:
-- Make sure to edit `YOUR_USERNAME_HERE` and `YOUR_PASSWORD_HERE`
-- To `YOUR_USERNAME_HERE`, set a plain username like `john`, not your full `@user:example.com` identifier
-- Set `admin=yes` to make the user an administrator of the Matrix server
+- Make sure to adjust `YOUR_USERNAME_HERE` and `YOUR_PASSWORD_HERE`
+- For `YOUR_USERNAME_HERE`, use a plain username like `john`, not your full identifier (`@user:example.com`)
+- Use `admin=yes` to make your user account an administrator of the Matrix server
 
 ```sh
-ansible-playbook -i inventory/hosts setup.yml --extra-vars='username=YOUR_USERNAME_HERE password=YOUR_PASSWORD_HERE admin=<yes|no>' --tags=register-user
+ansible-playbook -i inventory/hosts setup.yml --extra-vars='username=YOUR_USERNAME_HERE password=YOUR_PASSWORD_HERE admin=yes' --tags=register-user
 
 # Example: ansible-playbook -i inventory/hosts setup.yml --extra-vars='username=john password=secret-password admin=yes' --tags=register-user
 ```
 
+Feel free to create as many accounts (for friends, family, etc.) as you want. Still, perhaps you should grant full administrative access to your account only (with `admin=yes`), and others should be created with `admin=no`.
+
 For more information, see the documentation for [registering users](registering-users.md).
 
 ## Finalize the installation

docs/quick-start.md

@@ -134,16 +134,14 @@ To create your user account via this Ansible playbook, run the command below on
 **Notes**:
 - Make sure to adjust `YOUR_USERNAME_HERE` and `YOUR_PASSWORD_HERE`
 - For `YOUR_USERNAME_HERE`, use a plain username like `john`, not your full identifier (`@user:example.com`)
-- Use `admin=yes` or `admin=no` depending on whether you wish to make the user an administrator of the Matrix server
+- Use `admin=yes` to make your user account an administrator of the Matrix server
 
 ```sh
-ansible-playbook -i inventory/hosts setup.yml --extra-vars='username=YOUR_USERNAME_HERE password=YOUR_PASSWORD_HERE admin=<yes|no>' --tags=register-user
+ansible-playbook -i inventory/hosts setup.yml --extra-vars='username=YOUR_USERNAME_HERE password=YOUR_PASSWORD_HERE admin=yes' --tags=register-user
 
 # Example: ansible-playbook -i inventory/hosts setup.yml --extra-vars='username=john password=secret-password admin=yes' --tags=register-user
 ```
 
-ℹ️ *For an instruction to add other user accounts than yours, see [Registering users](registering-users.md).*
-
 ## Finalize server installation
 
 <sup>This section is optimized for this quick-start guide and is derived from the following full-documentation page: [Server Delegation](howto-server-delegation.md)</sup>

docs/registering-users.md

@@ -41,6 +41,8 @@ ansible-playbook -i inventory/hosts setup.yml --extra-vars='username=USERNAME_HE
 # Example: ansible-playbook -i inventory/hosts setup.yml --extra-vars='username=john password=secret-password admin=yes' --tags=register-user
 ```
 
+Feel free to register as many users (for friends, family, etc.) as you want. Still, perhaps you should grant full administrative access to your user account only (with `admin=yes`), and others should be created with `admin=no`.
+
 ⚠ **Warning**: If you're registering users against Matrix Authentication Service, do note that it [still insists](https://github.com/element-hq/matrix-authentication-service/issues/1505) on having a verified email address for each user. Upon a user's first login, they will be asked to confirm their email address. This requires that email sending is [configured](./configuring-playbook-email.md). You can also consult the [Working around email deliverability issues](./configuring-playbook-matrix-authentication-service.md#working-around-email-deliverability-issues) section for more information.
 
 ### Registering users manually for Synapse