Better readme

[ganego]

Hi, I just installed your tool and I think the readme should be improved.

• You state "adb (binary) should exist in project root folder". It's unclear from the doc what this is, since when getting the source zip, the root folder is the one with the readme.md file. Having adb there does not work, it needs to be in the src folder.
• You state one should use adb binary. You do not write, that I have to uncomment adb.set_core(Adb.EXTERNAL_TOOL_ADB) to do that. Also I was under the impression I would not have to install adb-shell when using adb binary, yet I have to do that. Please write in the readme, that you have to uncomment that line, or build something that autodetects adb binary or let one choose from within the program.

Thank you