Update tracer readme (2).
Update tracer readme (2).

alban/scope,alban/scope,weaveworks/scope,alban/scope,dilgerma/scope,alban/scope,dilgerma/scope,paulbellamy/scope,kinvolk/scope,dilgerma/scope,weaveworks/scope,kinvolk/scope,alban/scope,paulbellamy/scope,kinvolk/scope,dilgerma/scope,dilgerma/scope,alban/scope,weaveworks/scope,weaveworks/scope,kinvolk/scope,weaveworks/scope,kinvolk/scope,dilgerma/scope,paulbellamy/scope,kinvolk/scope,paulbellamy/scope,weaveworks/scope,paulbellamy/scope,paulbellamy/scope