Get Channel Messages endpoint should be more precise

[rayer456]

https://discord.com/developers/docs/resources/message#get-channel-messages doesn't specify anywhere that a Bearer token cannot use this endpoint. This endpoint seems to only be usable on guilds, however the description hints that private DM channels can be called upon, which they cannot.

[advaith1]

By default, documented endpoints can only be used by bots. If an endpoint is accessible through OAuth then the documentation will include the scope(s) necessary, but the majority of endpoints are not available via OAuth.

This endpoint is usable on DM channels.