docs: include Dart Frog with GraphQL example

[ayanfesolution]

Description

I am trying to use graphQL with Dartfrog but couldn't get any resources. Please can it be considered to be added to dartfrog

Requirements

• All CI/CD checks are passing.
• There is no drop in the test coverage percentage.

Additional Context

No response

[alestiago]

Seems to be related to #576, do you have any additional questions based on @wolfenrain comment: #576 (comment).

I'm starting to think that a GraphQL example with Dart Frog might be useful (cc @tomarra @wolfenrain).

[ayanfesolution]

A sample project and example added to the documentation of dart frog will be very wonderful, It will make it easy to take it further