Parameter help contains markup artifacts

[microbit-matt-hillsdon]

We get this back via LSP as a string not MarkupContent but I'm not sure whether Pyright is or should be trying to do restructured text -> markdown conversion.

I don't think these artifacts are present in VS Code.

Needs tracing end to end to understand what's going on and fix.

[microbit-matt-hillsdon]

If this used the code tag appropriately then maybe we could arrange for text to have the code formatting for consistency with API docs.

[microbit-matt-hillsdon]

There's a PR for the Pyright change here: https://github.com/microbit-foundation/pyright/pull/4/files