Links to help docs within SeaSketch

[wmcclin]

It would be great if we could add links to the help documents:

• Somewhere on the project page, link to: https://docs.seasketch.org/seasketch-documentation/users-guide/getting-started
• In various places admin dashboard, link to: https://docs.seasketch.org/seasketch-documentation/administrators-guide/getting-started
• Somewhere in the Sketch Classes section on the admin dashboard, also link to: https://github.com/seasketch/geoprocessing