add tasks.json

.vscode/tasks.json

+{
+    // See https://go.microsoft.com/fwlink/?LinkId=733558
+    // for the documentation about the tasks.json format
+    "version": "2.0.0",
+    "tasks": [
+        {
+            "label": "docker build",
+            "command": "docker",
+            "args": [
+                "build",
+                "."
+            ]
+        }
+    ]
+}