Documentation: amd-pstate: add tracer tool introduction

Documentation: amd-pstate: add tracer tool introduction

BugLink: https://bugs.launchpad.net/bugs/1998106
Add amd pstate tracer tool introduction

Signed-off-by: Jinzhou Su <Jinzhou.Su@amd.com>
Reviewed-by: Huang Rui <ray.huang@amd.com>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
(cherry picked from commit b020771a66e474cd8450b3c483cec8492702db22)
Signed-off-by: Paolo Pisati <paolo.pisati@canonical.com>
Acked-by: Tim Gardner <tim.gardner@canonical.com>
Acked-by: Cory Todd <cory.todd@canonical.com>
Signed-off-by: Luke Nowakowski-Krijger <luke.nowakowskikrijger@canonical.com>