build(deps): [security] bump prismjs from 1.20.0 to 1.21.0 in /docs (#1566)

Bumps [prismjs](https://github.com/PrismJS/prism) from 1.20.0 to 1.21.0. **This update includes a security fix.**
- [Release notes](https://github.com/PrismJS/prism/releases)
- [Changelog](https://github.com/PrismJS/prism/blob/master/CHANGELOG.md)
- [Commits](https://github.com/PrismJS/prism/compare/v1.20.0...v1.21.0)

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

Co-authored-by: dependabot-preview[bot] <27856297+dependabot-preview[bot]@users.noreply.github.com>

docs/package-lock.json

@@ -7741,9 +7741,9 @@
       "dev": true
     },
     "prismjs": {
-      "version": "1.20.0",
-      "resolved": "https://registry.npmjs.org/prismjs/-/prismjs-1.20.0.tgz",
-      "integrity": "sha512-AEDjSrVNkynnw6A+B1DsFkd6AVdTnp+/WoUixFRULlCLZVRZlVQMVWio/16jv7G1FscUxQxOQhWwApgbnxr6kQ==",
+      "version": "1.21.0",
+      "resolved": "https://registry.npmjs.org/prismjs/-/prismjs-1.21.0.tgz",
+      "integrity": "sha512-uGdSIu1nk3kej2iZsLyDoJ7e9bnPzIgY0naW/HdknGj61zScaprVEVGHrPoXqI+M9sP0NDnTK2jpkvmldpuqDw==",
       "dev": true,
       "requires": {
         "clipboard": "^2.0.0"