requesting changes in readme.md

In the multistage docker script, these __didn't__ work for me:

```bash
# Copy in the built dependencies
COPY --from=build-image ${FUNCTION_DIR} ${FUNCTION_DIR}
```
Doing the above resulted in:

`Error: Error loading shared library libnghttp2.so.14: No such file or directory (needed by /runnable/node_modules/aws-lambda-ric/build/Release/runtime-client.node)`

What worked for me is:

```bash
...

FROM build-image AS DEPLOYABLE

# Include global arg in this stage of the build
ARG FUNCTION_DIR

# Set working directory to function root directory
WORKDIR ${FUNCTION_DIR}

ENTRYPOINT ["/usr/local/bin/npx", "aws-lambda-ric"]
CMD ["app.handler"]
```

You might consider changing the README to use that instead?

Thanks!
Bryan