[CustomConfiguration] Add "Admin" section

Custom-Configuration.md

@@ -14,11 +14,12 @@ __Notice__: If a parameter is not specified in your `config.ini.php` RSS-Bridge
 
 # Available parameters
 
-The configuration file is split into three sections:
+The configuration file is split into four sections:
 
 * [cache](#cache)
 * [proxy](#proxy)
 * [authentication](#authentication)
+* [admin](#admin)
 
 _Cache_: This section is all about the caching behaviour of RSS-Bridge
 
@@ -26,6 +27,8 @@ _Proxy_: This section can be used to specify a proxy server for RSS-Bridge to ut
 
 _Authentication_: This section defines parameters to require authentication to use RSS-Bridge
 
+_Admin_: This section specifies parameters related to the administrator of your instance of RSS-Bridge
+
 ## Cache
 
 This section provides following parameters:
@@ -92,4 +95,20 @@ Defines the user name used for login.
 
 ### password
 
-Defines the password used for login. Use a strong password to prevent others from guessing your login!
+Defines the password used for login. Use a strong password to prevent others from guessing your login!
+
+## Admin
+
+This section provides following parameters:
+
+- [email](#email)
+
+### email
+
+Advertises an email address where people can reach the administrator.
+
+*Notice*: This address is displayed on the main page, visible to everyone!
+
+`""`    = Disabled (default)
+
+Example: `email = "admin@instance.rss-bridge.com"`