Prepared changes lists wrong key for multipv/depth

[lakinwecker]

https://github.com/niklasf/fishnet/blob/master/src/api.rs#L124-L127
https://github.com/niklasf/fishnet/blob/master/doc/protocol.md#prepared-changes

In the protocol.md doc, it lists work.analysis.multipv and work.analysis.depth but the actual code puts it directly in work.multipv and work.depth

Or maybe I'm reading that code wrong and maybe the entire thing goes in work.analysis including nodes and the thing that is wrong is the Response with work: from the doc?

[niklasf]

Oops. Confused the internal enum variant Work::Analysis with how it looks in JSON. Makes more sense to put these right next to nodes.