Remove note RE hiding new hint styles in mobile native apps
Remove note RE hiding new hint styles in mobile native apps

Summary:
With D28032, we're now using the Bibliotron hint styles in the mobile native apps. I've updated
the comment in `perseus.less` to reflect the new reality!

Test Plan: Verify that comments don't affect code behavior.

Auditors: david

learningequality/perseus,ariabuckles/perseus,ariabuckles/perseus,ariabuckles/perseus,ariabuckles/perseus,learningequality/perseus