Fix broken link in README for gatsby-plugin-react-helmet (#9891)

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packages/gatsby-plugin-react-helmet/README.md

@@ -26,4 +26,4 @@ plugins: [`gatsby-plugin-react-helmet`]
 ## Examples
 
 - [GatsbyJS.org](https://github.com/gatsbyjs/gatsby/blob/master/www/src/components/layout.js)
-- [Jason Lengstorf personal website](https://github.com/jlengstorf/lengstorf.com/blob/master/src/components/SEO.js)
+- [Jason Lengstorf personal website](https://github.com/jlengstorf/lengstorf.com/blob/master/src/components/SEO/SEO.js)