Update WCAG filters wording to be in line with WCAG-EM-Report Tool

[yatil]

Adapt final resolution of w3c/wcag-em-report-tool#317.

[shawna-slh]

Follow on from w3c/wcag-em-report-tool#317 (comment) :

While consistency is good, I'm hesitant to change the QuickRef now because lots of users are used to that interface.

A straw proposal for EOWG consideration:

• Leave QuickRef as it is for now.
• When we do an update for 2.2, then change it.