doc/mod/notification-matrix: describe how to declare functions...

... to use them in own scripts.

Author: eworm-de

doc/mod/notification-matrix.md

@@ -90,8 +90,8 @@ Usage and invocation
 There's nothing special to do. Every script or function sending a notification
 will now send it to your Matrix account.
 
-But of course you can send notifications directly or use a function in your
-own scripts. Give it a try:
+But of course you can use the function to send notifications directly. Give
+it a try:
 
     $SendMatrix "Subject..." "Body..."
 
@@ -100,6 +100,12 @@ methods:
 
     $SendNotification "Subject..." "Body..."
 
+To use the functions in your own scripts you have to declare them first.
+Place this before you call them:
+
+    :global SendMatrix;
+    :global SendNotification;
+
 See also
 --------