[cli] add `factoryreset` for Joiner in README_COMMISSIONING.md (#4868)
[cli] add `factoryreset` for Joiner in README_COMMISSIONING.md (#4868)


librasungirl/openthread,abtink/openthread,chshu/openthread,bukepo/openthread,srickardti/openthread,librasungirl/openthread,srickardti/openthread,lanyuwen/openthread,jwhui/openthread,jwhui/openthread,abtink/openthread,abtink/openthread,openthread/openthread,jwhui/openthread,bukepo/openthread,bukepo/openthread,lanyuwen/openthread,chshu/openthread,lanyuwen/openthread,chshu/openthread,openthread/openthread,chshu/openthread,lanyuwen/openthread,abtink/openthread,chshu/openthread,librasungirl/openthread,openthread/openthread,lanyuwen/openthread,lanyuwen/openthread,bukepo/openthread,chshu/openthread,openthread/openthread,librasungirl/openthread,srickardti/openthread,srickardti/openthread,jwhui/openthread