chore(docs): fix spelling on gatsby-plugin-feed (#14440)

Author: csellis

packages/gatsby-plugin-feed/README.md

@@ -78,7 +78,7 @@ Each feed must include `output`, `query`, and `title`. Additionally, it is stron
 
 `match` is an optional configuration, indicating which pages will have feed reference included. The accepted types of `match` are `string` or `undefined`. By default, when `match` is not configured, all pages will have feed reference inserted. If `string` is provided, it will be used to build a RegExp and then to test whether `pathname` of current page satisifed this regular expression. Only pages that satisifed this rule will have feed reference included.
 
-All additional options are passed through to the [`rss`][rss] utillity. For more info on those additional options, [explore the `itemOptions` section of the `rss` package](https://www.npmjs.com/package/rss#itemoptions).
+All additional options are passed through to the [`rss`][rss] utility. For more info on those additional options, [explore the `itemOptions` section of the `rss` package](https://www.npmjs.com/package/rss#itemoptions).
 
 Check out an example of [how you could implement](https://www.gatsbyjs.org/docs/adding-an-rss-feed/) to your own site, with a custom `serialize` function, and additional functionality.