Move Community Showcase to Docs

[cindyfirestone]

• Move Community Showcase Page https://reactioncommerce.com/community-showcase# into the Docs
• Add Community Showcase link/section under CONTRIBUTING GUIDE
• Update URL from See Examples of the homepage content block number 4 and footer link to redirect to the new docs URL
• Link to the docs in the footer

[machikoyasuda]

@cindyfirestone Should we also remove the Community Showcase link from the footer? Or change that footer link to the Docs link?

[cindyfirestone]

@machikoyasuda I say keep it in there, but link it to the docs. It's likely a lot of the business decision makers will not go to the docs.