Update Android documentation to include supported SDK levels

[JPercival]

Describe the issue
Currently the Android client documentation doesn't include the supported Android SDK levels, or any expectation on how that SDK level will evolve alongside HAPI releases, or which HAPI modules are able to be used on Android. The documentation should updated to included this information. Perhaps as a table like (made up information, not accurate):

HAPI Version	Android SDK	Modules
8.0	API Level 34	base, structures, android-client
7.6	API Level 26	base, structures, android-client
6.5	API Level 24	base, structures, android-client

Environment (please complete the following information):

• HAPI FHIR Version: 7.6.1

Additional context
I think we should target whatever SDK Google requires for a Google Play store release as of a given HAPI release date. For example, as of August 2024 Google is requiring a minimum target API level of 34:
https://developer.android.com/google/play/requirements/target-sdk

So, releases after August should target 34, release after the date Google requires 35 should target 35, etc.