Configuration mismatch between site_author and managingEditor

[martinbira]

The MkDocs configuration for site_author is corresponding to the managingEditor element according to the plugin documentation. However, the site_author populates the HTML meta tag, <meta name="author" content="Author Name">, and expects a name while the <managingEditor>-element expects an e-mail adress. This results in an invalid XML-file according to the W3C valdiator which in turn seems to not be processesed by some RSS readers.

Steps to reproduce

1. Create a basic MkDocs-site using with the mkdocs-rss-plugin.
2. Add site_author in the MkDocs configuration using a name and not an e-mail.
3. Do not use any other page meta author information.
4. Validate generated XML file with the W3C validator.

Suggestion Provide an override for managingEditor in the plugin configuration.