Add yaml language highlighting to readme (#30)

DavideViolante · web-flow · commit 31a8f9a1c657 · 2020-09-04T16:19:59.000+02:00
diff --git a/README.md b/README.md
@@ -13,7 +13,7 @@ Welcome, and thanks in advance for your help!
 An example workflow to deploy a project with serverless:
 
 
-```
+```yaml
 on:
   push:
     branches:
