Add docs on how to test Android Apps

### Contribution

- [ ] I'd be willing to implement this feature ([contributing guide](https://github.com/gemini-testing/hermione/blob/master/CONTRIBUTING.md))

### Describe the user story

There are no comprehensive guides on https://testplane.io related to Android apps testing. This prevents users from using Testplane for that purpose even though it has such capabilities.

### Describe the solution you'd like

Comprehensive guide on testplane.io

### Describe the drawbacks of your solution

_No response_

### Describe alternatives you've considered

_No response_