This option enables clipboard selection for most cases: Ctrl+L or F6 for URL bar selection; Ctrl+K for search bar selection; Esc to restore the original URL; Tab to focus either URL bar or search bar; or single-click or double-click selecting the entire text — if enabled.
From the web app, with option enabled:
Pressing CtrlL or F6 selects the URL bar, and copies to clipboard (i.e. a subsequent middle-click paste will paste the URL):
Pressing CtrlK selects the search bar, and copies to clipboard:
From the README; the part in bold is missing:
From the web app, with option enabled: