Update android_sdk.md (#578)

Fix images URL and replacing todo. Previous commit missed that

# What does this PR do?

In short, provide a summary of what this PR does and why. Usually, the
relevant context should be present in a linked issue.

- [ ] Addresses issue (#issue)


## Test Plan

Please describe:
 - tests you ran to verify your changes with result summaries.
 - provide instructions so it can be reproduced.


## Sources

Please link relevant resources if necessary.


## Before submitting

- [ ] This PR fixes a typo or improves the docs (you can dismiss the
other checks if that's the case).
- [ ] Ran pre-commit to handle lint / formatting issues.
- [ ] Read the [contributor
guideline](https://github.com/meta-llama/llama-stack/blob/main/CONTRIBUTING.md),
      Pull Request section?
- [ ] Updated relevant documentation.
- [ ] Wrote necessary unit or integration tests.

docs/source/distributions/index.md

@@ -35,6 +35,6 @@ If so, we suggest:
 
 - **Do you want to run Llama Stack inference on your iOS / Android device** If so, we suggest:
   - [iOS SDK](ondevice_distro/ios_sdk)
-  - Android (coming soon)
+  - [Android](ondevice_distro/android_sdk)
 
 You can also build your own [custom distribution](building_distro).