Update `doc` tool to be more outdir-flexible. (#490)
Update `doc` tool to be more outdir-flexible. (#490)

Net-net:

    dart tool/doc.dart -o $path_to_docs

will work if `$path_to_docs` is the lint rule subdir (as designed) but also if it’s the parent (a common mistake).
alexeieleusis/dart-lang_linter,dart-lang/linter,alexeieleusis/dart-lang_linter,dart-lang/linter