feat(docs): Message Content Intent in Migration Guide

[JustaSqu1d]

Summary

This introduces intents in the migration guide as it is also an important change.

Preview

Information

• This PR fixes an issue.
• This PR adds something new (e.g. new method or parameters).
• This PR is a breaking change (e.g. methods or parameters removed/renamed).
• This PR is not a code change (e.g. documentation, README, typehinting, examples, ...).

Checklist

• I have searched the open pull requests for duplicates.
• If code changes were made then they have been tested.
  • I have updated the documentation to reflect the changes.
• If type: ignore comments were used, a comment is also left explaining why.

[Dorukyum]

Are we sure intents default to Intents.none()?

pycord/discord/state.py

Lines 207 to 209 in 966f560

	intents = options.get("intents", None)
	if intents is None:
	intents = Intents.default()

[JustaSqu1d]

I was under the impression that it was None. I will say that Message Content is now also a Privileged intent, then.