Update README.md

Explain dependencies

README.md

@@ -7,8 +7,21 @@
 ```mermaid
 graph TD;
     Namespaces-->CRDs;
-    CRDs-->Crossplane;
+    CRDs-->Observability;
+    CRDs-->Security;
+    CRDs-->Infrastructure;
     Crossplane-->Infrastructure;
+    Crossplane-->Security;
+    Observability-->Apps;
     Infrastructure-->Apps;
     Security-->Apps;
+    Security-->Observability;
+    Security-->Infrastructure
 ```
+
+This diagram can be hard to understand so these are the key information:
+
+* Namespaces are the first resources to create, all other resources may be cluster scoped
+* CRDs that allow to extend Kubernetes capabilities must be present in order to use them in all other applications if needed.
+* Crossplane creates IRSA permissions which are required by some components
+* Security defines `external-secrets` that are needed by some applications in order to start.