shell_tools: Add warning about missing usage helpers
shell_tools: Add warning about missing usage helpers

Change-Id: Id1100c11f813032ff2ed6d7538faf4f1e2ee2b48
Signed-off-by: Adrian DC <01fb3892f39957945220431e7409156544d2f041@gmail.com>

AdrianDC/android_development_shell_tools,AdrianDC/android_development_shell_tools