build(deps): bump gatsby-plugin-offline from 3.2.21 to 3.2.22 in /docs

Bumps [gatsby-plugin-offline](https://github.com/gatsbyjs/gatsby/tree/HEAD/packages/gatsby-plugin-offline) from 3.2.21 to 3.2.22.
- [Release notes](https://github.com/gatsbyjs/gatsby/releases)
- [Changelog](https://github.com/gatsbyjs/gatsby/blob/master/packages/gatsby-plugin-offline/CHANGELOG.md)
- [Commits](https://github.com/gatsbyjs/gatsby/commits/gatsby-plugin-offline@3.2.22/packages/gatsby-plugin-offline)

Signed-off-by: dependabot[bot] <support@github.com>

Author: dependabot[bot]

docs/package-lock.json

@@ -21,7 +21,7 @@
     "gatsby-plugin-mdx": "^1.2.30",
     "gatsby-plugin-netlify": "^2.3.11",
     "gatsby-plugin-netlify-cache": "^1.2.0",
-    "gatsby-plugin-offline": "^3.2.21",
+    "gatsby-plugin-offline": "^3.2.22",
     "gatsby-plugin-react-helmet": "^3.3.10",
     "gatsby-plugin-react-svg": "^3.0.0",
     "gatsby-plugin-robots-txt": "^1.5.1",