Update the example for pfcwd start command#1984

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ZhaohuiS merged 2 commits intosonic-net:masterfrom

ZhaohuiS:fix_pfcwd_start_comments

Jan 5, 2022

Commits on Dec 23, 2021

example of pfcwd start command is a little confused, after execution, it says invalid options. Update it with a correct command
ZhaohuiS
committed

Commits on Jan 4, 2022

update other pfcwd start command examples
ZhaohuiS
committed