(docs): add gatsby-plugin-svgr to plugins list (#3250)

Author: zabute

docs/docs/plugins.md

@@ -142,6 +142,7 @@ root.
 * [gatsby-plugin-segment-js](https://github.com/benjaminhoffman/gatsby-plugin-segment-js)
 * [gatsby-plugin-stripe-checkout](https://github.com/njosefbeck/gatsby-plugin-stripe-checkout)
 * [gatsby-plugin-stripe-elements](https://github.com/njosefbeck/gatsby-plugin-stripe-elements)
+* [gatsby-plugin-svgr](https://github.com/zabute/gatsby-plugin-svgr)
 * [gatsby-plugin-yandex-metrika](https://github.com/viatsko/gatsby-plugin-yandex-metrika)
 * [gatsby-remark-emoji](https://github.com/Rulikkk/gatsby-remark-emoji)
 * [gatsby-remark-external-links](https://github.com/JLongley/gatsby-remark-external-links)