docs(contributing): enable contribution via devcontainer (#3970)

.devcontainer/devcontainer.json

@@ -0,0 +1,18 @@
+// For format details, see https://aka.ms/devcontainer.json
+{
+	"name": "Development environments on your infrastructure",
+
+	// Sets the run context to one level up instead of the .devcontainer folder.
+	"context": ".",
+
+	// Update the 'dockerFile' property if you aren't using the standard 'Dockerfile' filename.
+	"dockerFile": "Dockerfile",
+
+	// Use 'forwardPorts' to make a list of ports inside the container available locally.
+	// "forwardPorts": [],
+	
+	"postStartCommand": "dockerd",
+
+	// privileged is required by GitHub codespaces - https://github.com/microsoft/vscode-dev-containers/issues/727
+	"runArgs": [ "--cap-add=SYS_PTRACE", "--security-opt", "seccomp=unconfined", "--privileged", "--init" ]	
+}