Readme tweaks

I made a few tweaks to hopefully make the getting started flow clearer. I wanted it to be clear that:
- you need a project ID for the language examples
- and the browser tool is an alternative to using and writing code
Remove duplicate link

That link is also in the "what's next" section which seems like a good fit.
Add advanced examples link back
Merge pull request #1 from cassiedoll/readme

Readme tweaks