Plugin: categorized documentation via tags

Since our GraphQL schema grows we become lacking of some way to organize docs when using graphiql.

Currently there is existing a split on Query, Mutation and Subscription only. BTW on a large schema would be good to have some ability to categorize somehow those Queries, Mutation and Subscriptions. For example some meta tags in descriptions of objects could be helpful to notify graphiql that it should group/categorize them, or at least search by them... Currently search in docs working against types/fields names only, not by description.

Let's imagine it could be something like:

```graphql
"""Accounting entity @tag Payments"""
type Accounting implements Node {
"""The ID of an object"""
id: ID!

# ... other fields
}

"""Loan entity @tag Payments"""
type Loan implements Node {
"""The ID of an object"""
id: ID!

# ... other fields
}

# ...etc.
```

So now we could imagine, GraphiQL has an ability to organize docs in categories by `@tag`, or, at least `@tag` can be included in Docs explorer search...

Or, maybe, someone can point me to some existing known automated solution outside graphiql which can help us improve docs?