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/advanced/backend/entities/index.md

@@ -121,7 +121,7 @@ In the constructor, you can use dependency injection to get access to instances
 
 Then, in the method `list`, you can obtain an instance of the `PostRepository` using `this.manager_.getCustomRepository` passing it `this.postRepository` as a parameter. This lets you use [Custom Repositories with Typeorm](https://typeorm.io/custom-repository) to create custom methods in your repository that work with the data in your database.
 
-After getting an instance of the repository, you can then use [Typeorm’s Repository methods](https://typeorm.io/repository-api) to perform CRUD (Create, Read, Update, Delete) operations on your entity.
+After getting an instance of the repository, you can then use [Typeorm’s Repository methods](https://typeorm.io/repository-api) to perform Create, Read, Update, and Delete (CRUD) operations on your entity.
 
 If you need access to your entity in endpoints, you can then use the methods you define in the service.
 

docs/content/advanced/backend/entities/overview.md

@@ -2,7 +2,7 @@
 
 In this document, you'll learn what Entities are in Medusa.
 
-## What are Entities?
+## What are Entities
 
 Entities in medusa represent tables in the database as classes. An example of this would be the `Order` entity which represents the `order` table in the database. Entities provide a uniform way of defining and interacting with data retrieved from the database.