README include cmdline-tools in path to sdkmanager

[zachawilson]

Update README so that getting started section can be completed without incident.

Problem Solved

Following the Getting Started section of the README I run into an error because of invalid path in the step:
sdk/tools/bin/sdkmanager --update

Inspecting the directory it seems that the correct command needs the path update making the correct command be:
sdk/cmdline-tools/tools/bin/sdkmanager --update

Specifically these are the lines I ran into.

AndroidSDK/README.md

Lines 129 to 135 in 3d788b2

	# copy the pre-downloaded SDK to the mounted 'sdk' directory
	docker run -it --rm -v $(pwd)/sdk:/sdk thyrlian/android-sdk bash -c 'cp -a $ANDROID_SDK_ROOT/. /sdk'
	# go to the 'sdk' directory on the host, update the SDK
	# ONLY IF the host machine is the same target architecture as the container
	# JDK required on the host
	sdk/tools/bin/sdkmanager --update

I believe all of the other places this PR updates are appropriate changes too.

[thyrlian]

Thanks mate!

My bad, I thought I had already updated the README as part of this change, but it turned out not at all.

[thyrlian]

LGTM

[thyrlian]

I also made this minor change after merging your PR.
7c3778e

I didn't touch platform-tools, because it resides in ANDROID_SDK_ROOT, on the same level as cmdline-tools.