build(deps): bump prop-types from 15.7.2 to 15.8.0 in /docs (golangci#2444)

Author: dependabot[bot]

docs/package-lock.json

@@ -39,7 +39,7 @@
     "gatsby-transformer-yaml": "^2.11.0",
     "polished": "^4.1.3",
     "prism-react-renderer": "^1.2.1",
-    "prop-types": "^15.7.2",
+    "prop-types": "^15.8.0",
     "puppeteer": "^13.0.1",
     "react": "^17.0.2",
     "react-dom": "^17.0.2",