docs: add component library document

[janechu]

🙋 Documentation Request

The documentation located in the sites/website/ is currently undergoing updates for @microsoft/fast-element v2. At the moment we have a TODO for a document to set up a package that exports components as a library. This can be found here.

This document should give some examples and explain the basic structure and best practices that we recommend for the community when creating component libraries.

This is part of the next steps of #6972 and should assist in helping community members create projects and migrate from @microsoft/fast-foundation pursuant to our project re-alignment goals as seen in #6955 and #6951.