Create the framework for a MetaBrainz styleguide, to be populated over time.

'Style' in this case means the style of writing and comms that MetaBrainz uses throughout its projects, as well as externally. This includes things like our 'voice'/'personality', target audience, terms we use or avoid, when to use bold and italics, and so on.

The aim is to allow multiple people to write for MetaBrainz, without sacrificing consistency.