docs: integrate Vale for documentation linting (#2242)

* added value rules

* resolved errors raised by vale

* added github action

* fixes to github action

* added details in contribution guidelines

* added rule for numbers

* limited checks to errors

docs/content/user-guide/gift-cards/manage.mdx

@@ -107,7 +107,7 @@ To delete a denomination:
 
 :::info
 
-You can add up to 10 images for a Gift Card.
+You can add up to ten images for a Gift Card.
 
 :::