message: Added a line to README about --manifest-out option
diff: @@ -33,6 +33,7 @@ for this step).
  - `--exclude <path>`: Exclude a subpath from root. Use multiple times to exclude multiple paths. Tags (imports/scripts/etc) that reference an excluded path are left in-place, meaning the resources are not inlined. ex: `--exclude=elements/x-foo.html --exclude=elements/x-bar.html`
  - `--inline-scripts`: Inline external scripts.
  - `--inline-css`: Inline external stylesheets.
  +- `--manifest-out <path>`: If specified, the bundle manifest will be written out to `<path>`.
  - `--redirect <prefix>|<path>`: Routes URLs with arbitrary `<prefix>`, possibly including a protocol, hostname, and/or path prefix to a `<path>` on local filesystem. For example `--redirect "myapp://|src"` would route `myapp://main/home.html` to `./src/main/home.html`. Multiple redirects may be specified; the earliest ones have the highest priority.
  - `--shell`: Uses a bundling strategy which puts inlines shared dependencies into a specified html app "shell".
  - `--strip-comments`: Strips all HTML comments from the document which do not contain an `@license`, or start with `<!--#` or `<!--!`.
  