Fixes a factual error caught by the user directly questioning the "LibreWolf is currently running" refusal message: it claimed LibreWolf "rewrites user.js/prefs.js on exit," which isn't true. LibreWolf only ever reads user.js, once, at startup -- it never writes to it.
What's actually true: prefs.js (a different file -- the live preference state) is written on clean shutdown, which is the real reason applying/reverting requires LibreWolf closed. A new user.js written while the browser is open has no effect until the next full restart regardless.
Corrected the wording in the CLI's refusal message, install.sh's equivalent, and the man page.
Rebuilt, lintian-clean.