add http example README.md

With instructions on how to use docker-compose to run the example.

Signed-off-by: Andrew Hsu <[email protected]>

example/http/README.md

@@ -0,0 +1,24 @@
+# HTTP Client-Server Example
+
+An HTTP client connects to an HTTP server. They both generate span information to `stdout`.
+These instructions expect you have [docker-compose](https://docs.docker.com/compose/) installed.
+
+Bring up the `http-server` and `http-client` services to run the example:
+```sh
+docker-compose up --detach http-server http-client
+```
+
+The `http-client` service sends just one HTTP request to `http-server` and then exits. View the span generated to `stdout` in the logs:
+```sh
+docker-compose logs http-client
+```
+
+View the span generated by `http-server` in the logs:
+```sh
+docker-compose logs http-server
+```
+
+Shut down the services when you are finished with the example:
+```sh
+docker-compose down
+```