add handler for source update

roles/matrix-bridge-discord/handlers/main.yml

@@ -1 +1,5 @@
 ---
+- name: Re-build discord bridge
+  shell:
+    cmd: npm run build
+    chdir: /srv/matrix-appservice-discord

roles/matrix-bridge-discord/tasks/main.yml

@@ -37,7 +37,7 @@
   git:
     repo: 'https://github.com/t2bot/matrix-appservice-discord.git'
     dest: /srv/matrix-appservice-discord
-# They should be an handler here the rebuild the bot
+  notify: Re-build discord bridge
 
 - name: Build typescript
   shell: