Update readme

Author: juffalow

README.md

@@ -96,6 +96,14 @@ List all URLs in sitemap. If it is sitemap index (sitemap that contains URLs to
 pentest-tool-lite sitemap https://example.com/sitemap.xml
 ```
 
+#### Random
+
+Reads from standard input and outputs lines based on some probability. This can be used for testing just random urls. For example, you can run `sitemap` sub-command, but you don't want to run the pentest on all of listed urls, so you can use pipes and pick random urls.
+
+```
+pentest-tool-lite sitemap https://example.com/sitemap.xml | pentest-tool-lite random | xargs -n1 pentest-tool-lite
+```
+
 ## Contributing
 
 Use [GitHub issues](https://github.com/juffalow/pentest-tool-lite/issues) if you have suggestion for new check(s) or you found a bug in existing one.