Clarify documentation over visibility matchers
Clarify documentation over visibility matchers

artyom-razinov/EarlGrey,sskhandp/EarlGrey,google/EarlGrey,google/EarlGrey,sskhandp/EarlGrey,artyom-razinov/EarlGrey,google/EarlGrey,artyom-razinov/EarlGrey,artyom-razinov/EarlGrey,google/EarlGrey,artyom-razinov/EarlGrey,sskhandp/EarlGrey,sskhandp/EarlGrey,google/EarlGrey,sskhandp/EarlGrey