Bug 1858299 - moz.yaml file should not start with --- r=tjr

That's usually a requirement for yaml files, but this break updatebot,
so add an exception here.

Differential Revision: https://phabricator.services.mozilla.com/D190651

.yamllint

@@ -1,6 +1,11 @@
 ---
 extends: default
 
+rules:
+  document-start:
+    ignore: |
+      **/moz.yaml
+
 ignore: |
   *node_modules*
   *bad.yml

tools/fuzzing/libfuzzer/moz.yaml

@@ -1,6 +1,3 @@
----
----
-
 schema: 1
 
 bugzilla: