Update documentation of setting up double puppeting with bridges (#3837)

* Update docs/configuring-playbook-bridge-appservice-kakaotalk.md: fix the header for adjusting the playbook configuration

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

* Move sections "Set up Double Puppeting" under "Usage" as subsections for mautrix bridges and appservice kakaotalk

The changes in this commit reflect double puppeting configuration flow. Since the docs claim that double puppeting can be set up after enabling bridges by chatting with the bridge's bot, the explanation about double puppeting may well be placed under "Usage" as subsection.

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

* Remove notes about setting up double puppeting manually

Since this method is explained after configuring bridges, those notes are no longer necessary.

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

* Update docs for mautrix and kakaotalk bridges: add prerequisite(s) section for instructing to install Appservice Double Puppet and/or Shared Secret Auth service

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

* Replace "Enabling Appservice Double Puppet" with "This"

Enabling Appservice Double Puppet is contrasted with "Enabling double puppeting by enabling the Shared Secret Auth service", therefore it can be just called as "this" if Shared Secret Auth service is not mentioned below.

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

* Update docs/configuring-playbook-bridge-beeper-linkedin.md: follow other instances

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

* Add 💡 (Light Bulb: U+1F4A1) to the headings

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

---------

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

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

@@ -4,10 +4,22 @@ The playbook can install and configure [mautrix-signal](https://github.com/mautr
 
 See the project's [documentation](https://docs.mau.fi/bridges/python/signal/index.html) to learn what it does and why it might be useful to you.
 
-**Note/Prerequisite**: If you're running with the Postgres database server integrated by the playbook (which is the default), you don't need to do anything special and can easily proceed with installing. However, if you're [using an external Postgres server](configuring-playbook-external-postgres.md), you'd need to manually prepare a Postgres database for this bridge and adjust the variables related to that (`matrix_mautrix_signal_database_*`).
-
 **Note**: This revamped version of the [mautrix-signal (legacy)](configuring-playbook-bridge-mautrix-signal.md) may increase the CPU usage of your homeserver.
 
+## Prerequisites (optional)
+
+### Prepare Postgres database on external Postgres server
+
+If you're running with the Postgres database server integrated by the playbook (which is the default), you don't need to do anything special and can easily proceed with installing.
+
+However, if you're [using an external Postgres server](configuring-playbook-external-postgres.md), you'd need to manually prepare a Postgres database for this bridge and adjust the variables related to that (`matrix_mautrix_signal_database_*`).
+
+### Enable Appservice Double Puppet
+
+If you want to set up [Double Puppeting](https://docs.mau.fi/bridges/general/double-puppeting.html) (hint: you most likely do) for this bridge automatically, you need to have enabled [Appservice Double Puppet](configuring-playbook-appservice-double-puppet.md) service for this playbook.
+
+For details about configuring Double Puppeting for this bridge, see the section below: [Set up Double Puppeting](#-set-up-double-puppeting)
+
 ## Adjusting the playbook configuration
 
 To enable the bridge, add the following configuration to your `inventory/host_vars/matrix.example.com/vars.yml` file:
@@ -58,19 +70,23 @@ You may wish to look at `roles/custom/matrix-bridge-mautrix-signal/templates/con
 
 After configuring the playbook, run the [installation](installing.md) command: `just install-all` or `just setup-all`
 
-## Set up Double Puppeting
+## Usage
 
-If you'd like to use [Double Puppeting](https://docs.mau.fi/bridges/general/double-puppeting.html) (hint: you most likely do), you have 2 ways of going about it.
+You then need to start a chat with `@signalbot:example.com` (where `example.com` is your base domain, not the `matrix.` domain).
 
-### Method 1: automatically, by enabling Appservice Double Puppet
+### 💡 Set up Double Puppeting
 
-The bridge will automatically perform Double Puppeting if you enable the [Appservice Double Puppet](configuring-playbook-appservice-double-puppet.md) service for this playbook.
+After successfully enabling bridging, you may wish to set up [Double Puppeting](https://docs.mau.fi/bridges/general/double-puppeting.html) (hint: you most likely do).
+
+To set it up, you have 2 ways of going about it.
+
+#### Method 1: automatically, by enabling Appservice Double Puppet
+
+The bridge automatically performs Double Puppeting if [Appservice Double Puppet](configuring-playbook-appservice-double-puppet.md) service is configured and enabled on the server for this playbook.
 
 This is the recommended way of setting up Double Puppeting, as it's easier to accomplish, works for all your users automatically, and has less of a chance of breaking in the future.
 
-### Method 2: manually, by asking each user to provide a working access token
-
-**Note**: This method for enabling Double Puppeting can be configured only after you've already set up bridging (see [Usage](#usage)).
+#### Method 2: manually, by asking each user to provide a working access token
 
 When using this method, **each user** that wishes to enable Double Puppeting needs to follow the following steps:
 
@@ -79,8 +95,3 @@ When using this method, **each user** that wishes to enable Double Puppeting nee
 - send the access token to the bot. Example: `login-matrix MATRIX_ACCESS_TOKEN_HERE`
 
 - make sure you don't log out the `Mautrix-Signal` device some time in the future, as that would break the Double Puppeting feature
-
-
-## Usage
-
-You then need to start a chat with `@signalbot:example.com` (where `example.com` is your base domain, not the `matrix.` domain).