Add Freeplay to observability page

[jeremysilva1098]

Add details on the Freeplay <> Google ADK integration

[google-cla]

Thanks for your pull request! It looks like this may be your first contribution to a Google open source project. Before we can look at your pull request, you'll need to sign a Contributor License Agreement (CLA).

View this failed invocation of the CLA check for more information.

For the most up to date status, view the checks section at the bottom of the pull request.

[koverholt]

Thanks for the contribution and PR!

1. Formatting fixes and updates
   Since this code is in a fork, I'm unable to push updates directly in this PR. I posted my edited and cleaned-up version of this page in a gist (page, Markdown source). Would appreciate if you can push a commit with this version in this PR.

2. You'll need to sign a CLA before this PR can be merged. Refer to the logs in the failing CLA check for more info.

3. Suggest adding a list of resources and links in a new section at the bottom of the page, including Freeplay docs about the ADK integration, the sample repo, the Freeplay integration repo, etc.

Once we complete those steps, I can pass this to our technical writing team for further review. Thanks!

[jeremysilva1098]

@koverholt I've made the requested changes an completed the CLA, lmk if there is anything else!

[koverholt]

Thanks for the update! The CLA check is still failing - can you verify that the CLA exists for the same email address that you're committing with here?