[docs] Update Android Studio and Emulator instructions for SDK and Virtual Device Managers

Summary: Linear issue with full context and screenshots here. Minor change that updates the locations of the SDK and Virtual Device Managers, and also updates the renaming and relocating of the "Create device" button in the Virtual Device Manager.

Test Plan: N/A

Reviewers: ashoat, varun, atul

Reviewed By: ashoat, varun

Subscribers: palys-swm, Adrian, atul

Differential Revision: https://phab.comm.dev/D4257