chore: update android engine requirement <11.0.0

[erisu]

Platforms affected

Android

Motivation and Context

The Cordova Android platform has inegrated the Splash Screen plugin as core functionality.
This plugin is no longer needed in in the next majpr release of Cordova Android (11.0.0+).

Description

Update the engine requirement to not install on 11.0.0 or above.

Testing

Checklist

• I've run the tests to see all new and existing tests pass
• I added automated test coverage as appropriate for this change
• Commit is prefixed with (platform) if this change only applies to one platform (e.g. (android))
• If this Pull Request resolves an issue, I linked to the issue in the text above (and used the correct keyword to close issues using keywords)
• I've updated the documentation if necessary

[jcesarmobile]

Don’t understand the “If using cordova-android@11.x or later, use cordova-plugin-splashscreen@7.x (currently in-development).”

are we going to launch a 7.x version removing the android code?

[erisu]

Yes, 7.x will drop all of the Android code.

[erisu]

I just kept the wording to match how iOS was written.

It can be reworded as

If using cordova-android@11.x or later and exclusively developing for Android, this plugin can be uninstalled.

This entire section will be deleted in version 7.x anyways as the Android docs will be removed.
iOS For example, you can see the statement was removed in this upcoming PR: #331

It should have been removed when 6.0.0 released, but the docs were not migrated at the time.