chore: add checklist to verify the supported graphql types (#851)

* chore: add checklist to verify the supported graphql types

* update wordings

Author: sundersc

.github/PULL_REQUEST_TEMPLATE.md

@@ -34,6 +34,7 @@ List any codegen parameters changed or added.
 - [ ] Breaking changes to existing customers are released behind a feature flag or major version update
 - [ ] Changes are tested using sample applications for all relevant platforms (iOS/android/flutter/Javascript) that use the feature added/modified
 - [ ] Changes are tested on windows. Some Node functions (such as `path`) behave differently on windows.
+- [ ] Changes adhere to the [GraphQL Spec](https://spec.graphql.org/June2018/) and supports the GraphQL types `type`, `input`, `enum`, `interface`, `union` and scalar types.
 
 
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