message: Add link to default icons for links
diff: @@ -360,7 +360,7 @@ Fields of a link are:
  _NOTE_: The `icon` field value is meant to be a semantic key that will map to a
  specific icon that may be provided by an icon library (e.g. `material-ui`
  icons). These keys should be a sequence of `[a-z0-9A-Z]`, possibly separated by
  -one of `[-_.]`. Backstage may support some basic icons out of the box, but the
  +one of `[-_.]`. Backstage may support some basic icons out of the box such as those [defined in app-defaults](https://github.com/backstage/backstage/blob/master/packages/app-defaults/src/defaults/icons.tsx), but the
  Backstage integrator will ultimately be left to provide the appropriate icon
  component mappings. A generic fallback icon would be provided if a mapping
  cannot be resolved.
  