Add link to standard YAML file

Signed-off-by: Dave Thaler <dthaler@microsoft.com>

source-stewardship-extension.md

@@ -16,9 +16,10 @@ each with a date or date range.
 
 See also the [`_DATE` YAML file](yaml/_DATE.yaml) for more details.
 
-**Note**: the `_DATE YAML file is an anomaly here since `_DATE` is a
+**Note**: the `_DATE` YAML file is an anomaly here since `_DATE` is a
 [*relocated standard structure*](https://github.com/FamilySearch/GEDCOM/blob/main/specification/gedcom-1-hierarchical-container-format.md#extensions)
-which means it reuses the `g7:DATE` URI, which has its own YAML file already.
+which means it reuses the `g7:DATE` URI, which has its own
+[YAML file](https://github.com/FamilySearch/GEDCOM-registries/blob/main/structure/standard/DATE.yaml) already.
 There is an [issue](https://github.com/FamilySearch/GEDCOM.io/issues/97) tracking
 possible ways to allow automated validation of relocated standard structures,
 such as a wrapper YAML file.  In that light, an example YAML file is provided here that