fix: name --offline when given, keep page budget

--offline given with the variable set is named as the option, and the
runs the screen starts get it only when the user gave it. The first
install page stays under its 400 words, the 3.8 runs skip only the
pack test that needs generate_pack.

scripts/generate_installer_doc.py

@@ -154,7 +154,7 @@ def route_keys() -> str:
     return _table(heading, rows)
 
 
-def _marker(rule) -> str:
+def _marker(rule: _install._OsRule) -> str:
     """A card rule's evidence in words: the file or folder, and the line it
     holds for a rule that reads one."""
     if rule.method == "file_matches":