build(deps): bump gatsby-transformer-remark in /docs

Bumps [gatsby-transformer-remark](https://github.com/gatsbyjs/gatsby/tree/HEAD/packages/gatsby-transformer-remark) from 2.13.1 to 2.16.0.
- [Release notes](https://github.com/gatsbyjs/gatsby/releases)
- [Changelog](https://github.com/gatsbyjs/gatsby/blob/master/packages/gatsby-transformer-remark/CHANGELOG.md)
- [Commits](https://github.com/gatsbyjs/gatsby/commits/[email protected]/packages/gatsby-transformer-remark)

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

Author: dependabot[bot]

docs/package-lock.json

@@ -34,8 +34,8 @@
     "gatsby-remark-images": "^3.11.0",
     "gatsby-remark-mermaid": "^2.1.0",
     "gatsby-remark-responsive-iframe": "^2.11.0",
-    "gatsby-source-filesystem": "^2.8.1",
-    "gatsby-transformer-remark": "^2.13.1",
+    "gatsby-source-filesystem": "^2.11.0",
+    "gatsby-transformer-remark": "^2.16.0",
     "gatsby-transformer-sharp": "^2.12.0",
     "gatsby-transformer-yaml": "^2.8.0",
     "polished": "^4.1.0",