add a README tutorial on the mvc/overview example

Former-commit-id: c563c4f1ffa98705829e14b189a6976c3a6aa898

_examples/mvc/overview/Dockerfile

@@ -0,0 +1,17 @@
+# docker build -t app . 
+# docker run --rm -it -p 8080:8080 app:latest
+FROM golang:latest AS builder
+RUN apt-get update
+ENV GO111MODULE=on \
+    CGO_ENABLED=0 \
+    GOOS=linux \
+    GOARCH=amd64
+WORKDIR /go/src/app
+COPY go.mod .
+RUN go mod download
+COPY . .
+RUN go install
+
+FROM scratch
+COPY --from=builder /go/bin/app .
+ENTRYPOINT ["./app"]