clarify interactions with other browser extensions

[wont-work]

hey! i know last time google tried something to validate page integrity there was significant backlash due to perceived attempts to limit browser extensions such as ad blockers from modifying the page. from the documentation i've seen so far these browser-level modifications (usually authorized by the user, but can sometimes be malicious as well) does not seem to be something webcat intends to detect, but explicitly declaring this can be worthwhile to temper any potential backlash.

especially during this initial stage of the extension where, due to what i assume are browser limitations, CSP modifications done by extensions such as uBlock Origin (e.g. it's toggle to block all fonts), or by extensions like Stylus (to allow user CSS in pages with restrictive CSP) can be detected and blocked by webcat as well

[lsd-cat]

Thanks for filing this! Clearly our goal is to not interfere with other extensions. However, I currently haven't extensively tested whether that's the case or not: extension that operates on the DOM shouldn't have particular issues, while extension that use the same interception APIs might have problem, depending on which one acts first. It's good to keep this issue for tracking these potential problems, if we encounter any, and try to see what we can do about them!