Switch docs back to openrpc v2

[acolytec3]

This replaces the #653 docs project with the OpenRPC v2 docs generator so reverts back to the Gatsby build for now, based on #660.

Major changes

• Replace docusaurus docs builder with OpenRPC v2 generator (i.e. gatsby)
• Remove extraneous docusaurus artifacts
• Adds prepare-docs script that copies markdown files from docs to Gatsby build directory
• Adds gatsby-config that dynamically adds all markdown docs from docs to the sidebar

Miscellaneous

• Fixes spelling CI failures left over from add eth_simulateV1 #484

[acolytec3]

It now renders like this:

[acolytec3]

We should be sure to squash all this to one commit if/when merged.