Fix docstrings for task/blktrace.py, peering_speed_test.py, proc_thrasher.py and
recovery_bench.py.

Fixes: 6535
Signed-off-by: Warren Usui <warren.usui@inktank.com>
Merge pull request #197 from ceph/wip-6535-wusui

Fix docstrings for task/blktrace.py, peering_speed_test.py, proc_thrashe...