brew install httrack lands a working GUI that nothing tells Mac users about

[xroche]

The homebrew-core formula runs around 3,300 installs a month. It installs webhttrack into bin next to httrack and strips only the GNOME pixmaps and .desktop entry, so the GUI works. It carries no caveats block, so nobody is told it is there. #890 added a macOS note to html/guide.html, which only reaches someone already reading the guide.

Two places are left and both sit outside this repo: a caveats line in the formula pointing at webhttrack (and at HTTrack.app once a bundle is published), and the httrack.com download page, which currently offers no macOS GUI at all.

Split out of #886.

[xroche]

Half of this is done. httrack.com's download page has carried a macOS row since the DMG shipped (www/page2.inc, the arm64 alpha below the Android row), so "offers no macOS GUI at all" no longer holds.

What is left is the formula. Formula/h/httrack.rb in homebrew-core still has no caveats block: it strips share/{applications,pixmaps} and installs webhttrack into bin with nothing announcing it. One caveats stanza naming webhttrack is the whole fix, and it belongs in a PR to homebrew-core, not here.