Update Design & Modeling Sections

Update both Design and Modeling sections of Cps-Core Documentation

Issue-ID: CPS-626
Change-Id: I7b42e0bcedbec8d973557140c503828e33239847
Signed-off-by: DylanB95EST <dylan.byrne@est.tech>
Signed-off-by: lukegleeson <luke.gleeson@est.tech>
diff --git a/docs/api/yang/dmiYangResource.yang b/docs/api/yang/dmiYangResource.yang
new file mode 100644
index 0000000..8e06a26
--- /dev/null
+++ b/docs/api/yang/dmiYangResource.yang
@@ -0,0 +1,46 @@
+module dmi-registry {
+
+  yang-version 1.1;
+
+  namespace \"org:onap:cps:ncmp\";
+
+  prefix dmi-reg;
+
+  organization \"Nordix Foundation\";
+
+  contact \"rahul.tyagi@est.tech\";
+
+  revision \"2021-05-20\" {
+    description
+    \"Initial Version\";
+  }
+
+  container dmi-registry {
+
+    list cm-handles {
+
+      key \"id\";
+
+      leaf id {
+        type string;
+      }
+
+      leaf dmi-service-name {
+        type string;
+      }
+
+      list additional-properties {
+
+        key \"name\";
+
+        leaf name {
+          type string;
+        }
+
+        leaf value {
+          type string;
+        }
+      }
+    }
+  }
+}
\ No newline at end of file