This is a followup to bug 794980 comment 1.

I checked the usage of <app> vs. <gui> in the help docs and spotted one instance where <gui> was used instead of app:

> bug-filing.page:21: The <gui>image viewer</gui> is maintained by a volunteer  community.  You are welcome to participate.

This should likely use <app> instead.

Also, capitalizing these may improve the notion of being an app title:

> bug-filing.page:7:    <desc>File a bug against the <app>image viewer</app>.</desc>
> default.page:30:  <p>In the <app>files app</app>, right click the file and choose
> edit.page:42:  <p>The <app>image viewer</app> will detect that the 
open.page:23:double-click them in the <app>files</app> file browser. If this is not the
> plugin-send-by-mail.page:34: <p><app>Evolution mail</app> must be set up to connect to your email account