Workspaces page does not mention support for `package.json` in members

[lucacasonato]

Workspaces can have multiple workspace members. Each of these members can contain:

• just a deno.json
• a deno.json and a package.json
• just a package.json

When a member contains just a package.json, you can import that workspace member from other places in the workspace using the name specified in the package.json.

Currently this is not something we mention in the documentation.