Put clarifying language in migration guide regarding the serde:: and non-serde:: paths

[mcclure]

This past week I ported a crate from bincode1 to bincode2. I had some difficulty because I took the "migrate serde to bincode-derive" path, which was not appropriate for my application. I was following the migration guide, but I misread it.

I would like to recommend some minor language tweaks to make the migration guide more resistant to misinterpretation. Proposed language is attached, but I don't care if you use my specific language. I do suggest you make some form of the following changes:

• Make it clearer that the "Migrating with serde" and "Migrating to bincode-derive" sections describe exclusive options.
• Describe why someone might want to intentionally migrate with serde.

This would have helped me do my porting correctly the first time.

[stale]

This issue has been automatically marked as stale because it has not had recent activity. It will be closed if no further activity occurs. Thank you for your contributions.

[mcclure]

Nothing has changed, so this problem is still real. I still think this patch should be merged.

[VictorKoenders]

Please fix the change I've requested and we can get this merged

[mcclure]

Sorry, I misunderstood your comment before. Is that better?

[VictorKoenders]

Thanks!