Fix description how to start examples without docker

[rewop]

I tried the instructions in the README.md to start the examples without docker, and the url http://localhost:8080/webpack-dev-server/ doesn't work when the example start.

It works though with http://localhost:8080/.

I suggest anyway to only use docker, and make sure the examples can be run with the published version in npm, and optionally with the repository itself for development purposes

[rewop]

I am also noticing that the examples pages are not working properly. There are crashes happening. But I haven't found how to reproduce yet.

[tomchentw]

This is no longer needed given 6.0.0 removes the docker example. We could put it in somehow. Feel free to open another ticket there.

6.0.0 is released on npm beta tag now. See the changelog here. We also have a new demo page. Feel free to try it:
https://tomchentw.github.io/react-google-maps/