Update google-app-engine.md

Author: stb13579

docs/developer-docs/latest/setup-deployment-guides/deployment/hosting-guides/google-app-engine.md

@@ -306,18 +306,22 @@ export default ({ env }) => ({
 </code-group>
 
 ### Troubleshooting
-** unknown: Service 'containerregistry.googleapis.com' is not enabled for consumer **
+The following are common issues during deployment:
+
+#### `unknown: Service 'containerregistry.googleapis.com' is not enabled for consumer`
+
 Solution:
-1. Type "containerregistry" in the search input of Google cloud panel
-2. In search results select item with an API icon
-3. Disable and enable it again
-4. Find and enable CloudBuild API
-5. Deploy your project
+1. Type `containerregistry` in the search input of Google cloud panel.
+2. In search results select the item with an API icon.
+3. Disable and enable it again.
+4. Find and enable CloudBuild API.
+5. Deploy your project.
+
+#### `connect ECONNREFUSED /cloudsql/strapi-0000:europe-west1:strapi/.s.PGSQL.5432`
 
-** connect ECONNREFUSED /cloudsql/strapi-0000:europe-west1:strapi/.s.PGSQL.5432 **
 Solution:
-1. Find Cloud SQL Admin API
-2. Enable it 
-3. Deploy your project
+1. Find the Cloud SQL Admin API.
+2. Enable the Cloud SQL Admin API.
+3. Deploy your project.