Add support for d2lang

testdata/codes.md

@@ -65,3 +65,56 @@ graph TD;
     B-->D;
     C-->D;
 ```
+
+```d2
+vars: {
+  d2-config: {
+    layout-engine: elk
+    # Terminal theme code
+    theme-id: 300
+  }
+}
+network: {
+  cell tower: {
+    satellites: {
+      shape: stored_data
+      style.multiple: true
+    }
+
+    transmitter
+
+    satellites -> transmitter: send
+    satellites -> transmitter: send
+    satellites -> transmitter: send
+  }
+
+  online portal: {
+    ui: {shape: hexagon}
+  }
+
+  data processor: {
+    storage: {
+      shape: cylinder
+      style.multiple: true
+    }
+  }
+
+  cell tower.transmitter -> data processor.storage: phone logs
+}
+
+user: {
+  shape: person
+  width: 130
+}
+
+user -> network.cell tower: make call
+user -> network.online portal.ui: access {
+  style.stroke-dash: 3
+}
+
+api server -> network.online portal.ui: display
+api server -> logs: persist
+logs: {shape: page; style.multiple: true}
+
+network.data processor -> api server
+```