Add documentation comments for GraphQL APIs, if they are missing

[sophie-cluml]

It would be helpful to provide client-side friendly GraphQL API documentation, allowing client-side development to proceed without needing to understand the details of review-web. Developers could simply reference the GraphQL API schema, typically in SDL format. Some APIs have documentation, but not all are documented. So, I think this would mainly involve adding missing documentation comments in the relevant code.

[sehkone]

Regarding the APIs to return values parsed from packets, we need to not only fill in the missing ones but also ensure their descriptions are legitimate according to the standard protocols. Since the current API names do not clearly indicate the meaning of the values they return, it would be better to elaborate on them with descriptive texts. I asked Parker and Ben to add proper descriptions to each API in Notion, and I think this issue should be addressed after that is completed.