Add HCL Examples & Docs (#852)

Fixes https://github.com/pulumi/pulumi-docker-build/issues/844

examples/hcl/Pulumi.yaml

@@ -0,0 +1,10 @@
+name: provider-docker-build
+runtime: hcl
+config:
+  dockerHubPassword:
+    type: string
+    secret: true
+plugins:
+  providers:
+    - name: docker-build
+      path: ../../bin