[various] Remove config/addon.config.php in favor of per-addon configuration file

phpmailer/README.md

@@ -8,45 +8,7 @@ This addon replaces the default `mail()` function by the `PHPMailer` library, al
 Configuration
 -------------
 
-You can override the default value of the following config keys in your base Friendica install `config/addon.config.php` file:
-
-	'phpmailer' => [
-        // smtp (Boolean)
-        // Enables SMTP relaying for outbound emails
-        'smtp' => false,
-
-        // smtp_server (String)
-        // SMTP server host name
-        'smtp_server' => 'smtp.example.com',
-
-        // smtp_port (Integer)
-        // SMTP server port number
-        'smtp_port' => 25,
-
-        // smtp_secure (String)
-        // What kind of encryption to use on the SMTP connection.
-        // Options: '', 'ssl' or 'tls'.
-        'smtp_secure' => '',
-
-        // smtp_port_s (Integer)
-        // Secure SMTP server port number
-        'smtp_port_s' => 465,
-
-        // smtp_username (String)
-        // SMTP server authentication user name
-        // Empty string disables authentication
-        'smtp_username' => '',
-
-        // smtp_password (String)
-        // SMTP server authentication password
-        // Empty string disables authentication
-        'smtp_password' => '',
-
-        // smtp_from (String)
-        // From address used when using the SMTP server
-        // Example: no-reply@example.com
-        'smtp_from' => '',
-    ],
+The configuration options for this module are described in the `config/phpmailer.config.php` file.
 
 License
 =======

phpmailer/config/phpmailer.config.php

@@ -1,7 +1,7 @@
 <?php
 
 // Warning: Don't change this file! It only holds the default config values for this addon.
-// Instead overwrite these config values in config/addon.config.php in your Friendica directory
+// Instead, copy this file to config/phpmailer.config.php in your Friendica directory and set the correct values there
 
 return [
 	'phpmailer' => [