build(deps): bump gatsby-plugin-robots-txt from 1.5.1 to 1.6.2 in /docs

Bumps [gatsby-plugin-robots-txt](https://github.com/mdreizin/gatsby-plugin-robots-txt) from 1.5.1 to 1.6.2.
- [Release notes](https://github.com/mdreizin/gatsby-plugin-robots-txt/releases)
- [Commits](mdreizin/gatsby-plugin-robots-txt@v1.5.1...v1.6.2)

Signed-off-by: dependabot[bot] <[email protected]>

Author: dependabot[bot]

docs/package-lock.json

@@ -23,7 +23,7 @@
     "gatsby-plugin-offline": "^3.10.2",
     "gatsby-plugin-react-helmet": "^3.10.0",
     "gatsby-plugin-react-svg": "^3.0.1",
-    "gatsby-plugin-robots-txt": "^1.5.1",
+    "gatsby-plugin-robots-txt": "^1.6.2",
     "gatsby-plugin-sharp": "^2.14.4",
     "gatsby-plugin-sitemap": "^2.12.0",
     "gatsby-remark-autolink-headers": "^2.11.0",