Merge EVM docs into docs

[nsjames]

We want to merge the https://github.com/eosnetworkfoundation/evmdocs into the docs github so that they are on the same documentation.

This should be in an EVM sidebar item which is also on the navbar as one of the Learn options.

AC:

• Reformat docs to our formats
• Merge in EVM docs into the sidebar
• Add EVM into the navbar under Learn (https://github.com/eosnetworkfoundation/docsgen/blob/master/config/docusaurus.config.js)
• Build for staging
• Build for production

[iamveritas]

PR https://github.com/eosnetworkfoundation/docs/pull/49