Add graphql documentation

docs/architecture/application/graphql.md

@@ -0,0 +1,39 @@
+# GraphQL documentation
+
+OrchestratorCore comes with a graphql interface that can to be registered after you create your OrchestratorApp.
+If you add it after registering your `SUBSCRIPTION_MODEL_REGISTRY` it will automatically create graphql types for them.
+
+example:
+```python
+app = OrchestratorCore(base_settings=AppSettings())
+# register SUBSCRIPTION_MODEL_REGISTRY
+app.register_graphql()
+```
+
+## Extending the Query and Mutation
+
+This is an basic example of how to extend the query.
+You can do the same to extend Mutation.
+
+```python
+from orchestrator.graphql import Query, Mutation
+
+
+# Queries
+def resolve_new(info) -> str:
+    return "resolve new..."
+
+
+@strawberry.federation.type(description="Orchestrator queries")
+class NewQuery(Query):
+    other_processes: Connection[ProcessType] = authenticated_field(
+        resolver=resolve_processes,
+        description="resolve_processes used for another field",
+    )
+    new: str = strawberry.field(resolve_new, description="new resolver")
+
+
+app = OrchestratorCore(base_settings=AppSettings())
+# register SUBSCRIPTION_MODEL_REGISTRY
+app.register_graphql(query=NewQuery)
+```