Add section which explains how to configure PuTTY to use RTT
shell there with all shell features. There is an alternative
approach which also works but it does not allow to use all
shell features.
Signed-off-by: Krzysztof Chruściński <krzysztof.chruscinski@nordicsemi.no>
Supplemental information on shell command execution. Added an
illustration and four examples showing how the shell will call
the handler and what it will pass as an argument.
Signed-off-by: Jakub Rzeszutko <jakub.rzeszutko@nordicsemi.no>
