Add missing YAML files to Triggers sync config

The samples for the two 'Getting Started' links at the end of the main
Triggers page in the docs are missing so the links result in 404.

Add the YAML files to the sync config so they'll be included and available
from the links on the website.

sync/config/triggers.yaml

@@ -33,5 +33,7 @@ tags:
   - triggertemplates.md: triggertemplates.md
   - clustertriggerbindings.md: clustertriggerbindings.md
   - cel_expressions.md: cel_expressions.md
+  - create-ingress.yaml: create-ingress.yaml
+  - create-webhook.yaml: create-webhook.yaml
 # The link to the GitHub tag page.
 archive: https://github.com/tektoncd/triggers/tags