TO BE WRITTEN
Like other web resources, a web app manifest should be accessible to any web browser or web crawler.
If a web app developer wants to inform web crawlers of a desire for the file not to be crawled, the developer MAY do so by including the web app manifest in a robots.txt file.
This is further described in the robots.txt protocol.
A web app developer could also use the X-Robots-Tag
HTTP header.