Fix typo in perf design doc?
Fix typo in perf design doc?

s/clusting/clustering

BUG=None
TEST=None
R=jcgregorio@google.com
NOTRY=true

Author: tfarina@chromium.org

Review URL: https://codereview.chromium.org/584333002

google/skia-buildbot,google/skia-buildbot,google/skia-buildbot,google/skia-buildbot,google/skia-buildbot,Tiger66639/skia-buildbot,Tiger66639/skia-buildbot,Tiger66639/skia-buildbot,Tiger66639/skia-buildbot,google/skia-buildbot,google/skia-buildbot,Tiger66639/skia-buildbot,google/skia-buildbot,Tiger66639/skia-buildbot,Tiger66639/skia-buildbot