Add Landfast Sea Ice, Wet Days Per Year, and Beetle dataset download/documentation links to API documentation when they are ready

[cstephen]

Incorporate these links into the API documentation similar to how we have linked to other datasets hosted from GeoNetwork (e.g., Temperature, Precipitation, Snowfall Equivalent, etc.).

[brucecrevensten]

Landfast ice may not be available or a while, as that endpoint is in-progress and that's OK. (May want to split that one off from this ticket).