Bump axios from 0.19.2 to 0.21.2 in /docs

Bumps [axios](https://github.com/axios/axios) from 0.19.2 to 0.21.2.
- [Release notes](https://github.com/axios/axios/releases)
- [Changelog](https://github.com/axios/axios/blob/master/CHANGELOG.md)
- [Commits](axios/axios@v0.19.2...v0.21.2)

---
updated-dependencies:
- dependency-name: axios
  dependency-type: direct:production
...

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

Author: dependabot[bot]

docs/package-lock.json

@@ -7,7 +7,7 @@
     "doc": "docs"
   },
   "dependencies": {
-    "axios": "^0.19.2",
+    "axios": "^0.21.2",
     "download": "^7.1.0",
     "gitbook-cli": "^2.3.2",
     "gitbook-plugin-3-ba": "^0.9.0",