Add Build-A-Node page

[darkdrgn2k]

For content for the new Build A Node page i think it best to just pull from the existing prototype-cjdns-pi readme.md

This solution uses a new plugin to use remote_markdown to pull the fly on the fly

[benhylau]

This wouldn't rebuild tomesh.net when the remote md file changes. @garrying Is it easy to add that hook to what we currently use to trigger rebuilds?

[darkdrgn2k]

I'll leave it @garrying discretion as i'm not an expert on this by any stretch of the imagination.

This is a working solution (maybe intern solution?) and by my understanding the side DOES rebuild every night, so at worst the remote file would be 24 hours old (maybe 48 if it doesn't rebuild properly the first night)

But if there is a better solution that some one is willing to put together im all for it 🥇

[benhylau]

Yes I think we can merge this in its current state, but @garrying if it's adding an extra URL to watch, sure :)

[dcwalk]

This is awesome! However isn't linked from anywhere...?

[darkdrgn2k]

See #172 in global navigation rework