fix: Fix call event listener name + Added Call example (#1886)

* fix: bugfix + example

* relocate global variable

example.js

@@ -257,6 +257,15 @@ client.on('change_state', state => {
     console.log('CHANGE STATE', state );
 });
 
+// Change to false if you don't want to reject incoming calls
+let rejectCalls = true;
+
+client.on('call', async (call) => {
+    console.log('Call received, rejecting. GOTO Line 261 to disable', call);
+    if (rejectCalls) await call.reject();
+    await client.sendMessage(call.from, `[${call.fromMe ? 'Outgoing' : 'Incoming'}] Phone call from ${call.from}, type ${call.isGroup ? 'group' : ''} ${call.isVideo ? 'video' : 'audio'} call. ${rejectCalls ? 'This call was automatically rejected by the script.' : ''}`);
+});
+
 client.on('disconnected', (reason) => {
     console.log('Client was logged out', reason);
 });