feat(settings): Add model tag for ExtrnalLink model

ref: #833 #835 closes #584

app/settings/models/external_link.py

@@ -10,6 +10,8 @@ class ExternalLink(
     CenturionModel
 ):
 
+    model_tag = 'external_link'
+
 
     class Meta:
 

app/settings/tests/unit/external_links/test_unit_external_links_model.py

@@ -20,8 +20,7 @@ class AppSettingsModelTestCases(
 
         return {
             'model_tag': {
-                'type': models.fields.NOT_PROVIDED,
-                'value': models.fields.NOT_PROVIDED
+                'value': 'external_link'
             },
         }
 
@@ -113,10 +112,4 @@ class AppSettingsModelPyTest(
     AppSettingsModelTestCases,
 ):
 
-        def test_model_tag_defined(self, model):
-            """ Model Tag
-
-            Ensure that the model has a tag defined.
-            """
-
-            pytest.xfail( reason = 'Model does not require tag' )
+    pass

docs/projects/centurion_erp/user/core/markdown.md

@@ -80,7 +80,7 @@ A Model link is a reference to an item within the database. Supported model link
 | devicemodel| `$device_model-<id>` |
 | devicetype| `$device_type-<id>` |
 | entity | `$entity-<id>` |
-| externallink| `$-<id>` |
+| externallink| `$external_link-<id>` |
 | featureflag| `$feature_flag-<id>` |
 | gitrepository| `$git_repository-<id>` |
 | gitgroup| `$git_group-<id>` |