Text that is displayed after you click on browser RSS icon depends on the feed reader you are using. I don’t think you can modify what it displays directly through WordPress (correct me if I’m wrong).
A simple workaround to achieve something similar to what you want would be placing feed links to different categories. You can place a link for every category somewhere on the page using get_category_feed_link()
function.
Edit:
Some feed readers (Chrome’s RSS feed Reader) get feeds from sites header. In this case you can get them to display feed by adding link directly to header.php
inside the <head>
. Link could be formatted something like this:
<link rel="alternate" type="application/rss+xml" title="Category1 feed" href="https://wordpress.stackexchange.com/questions/176718/<?php echo get_category_feed_link( get_cat_ID("category1' ) ); ?>" />