Only use "cite-as" link to refer to main publication for data.

Previous to this commit, the 'cite-as' rel type was used to describe
links to both the main publication for the dataset as well as any
publications citing the data as listed in the 'publications'
property. As discussed in radiantearth#915, this can cause confusion as to how the
data should be cited. This change specifies that only the main
publication descripting the data should have a link with 'cite-as' as
the rel type in the links section.

Fixes radiantearth#915

extensions/scientific/README.md

@@ -56,7 +56,7 @@ This extension adds the following types as applicable `rel` types for the [Link
 
 | Type    | Description |
 | ------- | ----------- |
-| cite-as | For all DOI names specified the respective DOI links SHOULD be added to the links section with the `rel` type `cite-as` (see the [RFC 8574](https://tools.ietf.org/html/rfc8574)). |
+| cite-as | A DOI link SHOULD be added to the links section for the publication referenced by the `sci:doi` property with the `rel` type `cite-as` (see the [RFC 8574](https://tools.ietf.org/html/rfc8574)). |
 
 ## Implementations
 

extensions/scientific/examples/collection.json

@@ -38,10 +38,6 @@
     {
       "rel": "cite-as",
       "href": "https://doi.org/10.5061/dryad.s2v81.2"
-    },
-    {
-      "rel": "cite-as",
-      "href": "https://doi.org/10.1038/sdata.2017.78"
     }
   ]
 }

extensions/scientific/examples/item.json

@@ -49,14 +49,6 @@
     {
       "rel": "cite-as",
       "href": "https://doi.org/10.5061/dryad.s2v81.2/27.2"
-    },
-    {
-      "rel": "cite-as",
-      "href": "https://doi.org/10.5061/dryad.s2v81.2"
-    },
-    {
-      "rel": "cite-as",
-      "href": "https://doi.org/10.1038/sdata.2017.78"
     }
   ],
   "assets": {