Bump prismjs from 1.16.0 to 1.21.0 in /docs

Bumps [prismjs](https://github.com/PrismJS/prism) from 1.16.0 to 1.21.0.
- [Release notes](https://github.com/PrismJS/prism/releases)
- [Changelog](https://github.com/PrismJS/prism/blob/master/CHANGELOG.md)
- [Commits](PrismJS/prism@v1.16.0...v1.21.0)

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

docs/yarn.lock

@@ -2066,9 +2066,9 @@ cli-boxes@^2.2.0:
   integrity sha512-gpaBrMAizVEANOpfZp/EEUixTXDyGt7DFzdK5hU+UbWt/J0lB0w20ncZj59Z9a93xHb9u12zF5BS6i9RKbtg4w==
 
 clipboard@^2.0.0:
-  version "2.0.4"
-  resolved "https://registry.yarnpkg.com/clipboard/-/clipboard-2.0.4.tgz#836dafd66cf0fea5d71ce5d5b0bf6e958009112d"
-  integrity sha512-Vw26VSLRpJfBofiVaFb/I8PVfdI1OxKcYShe6fm0sP/DtmiWQNCjhM/okTvdCo0G+lMMm1rMYbk4IK4x1X+kgQ==
+  version "2.0.6"
+  resolved "https://registry.yarnpkg.com/clipboard/-/clipboard-2.0.6.tgz#52921296eec0fdf77ead1749421b21c968647376"
+  integrity sha512-g5zbiixBRk/wyKakSwCKd7vQXDjFnAMGHoEyBogG/bw9kTD9GvdAvaoRR1ALcEzt3pVKxZR0pViekPMIS0QyGg==
   dependencies:
     good-listener "^1.2.2"
     select "^1.1.2"
@@ -5996,9 +5996,9 @@ pretty-time@^1.1.0:
   integrity sha512-28iF6xPQrP8Oa6uxE6a1biz+lWeTOAPKggvjB8HAs6nVMKZwf5bG++632Dx614hIWgUPkgivRfG+a8uAXGTIbA==
 
 prismjs@^1.13.0:
-  version "1.16.0"
-  resolved "https://registry.yarnpkg.com/prismjs/-/prismjs-1.16.0.tgz#406eb2c8aacb0f5f0f1167930cb83835d10a4308"
-  integrity sha512-OA4MKxjFZHSvZcisLGe14THYsug/nF6O1f0pAJc0KN0wTyAcLqmsbE+lTGKSpyh+9pEW57+k6pg2AfYR+coyHA==
+  version "1.21.0"
+  resolved "https://registry.yarnpkg.com/prismjs/-/prismjs-1.21.0.tgz#36c086ec36b45319ec4218ee164c110f9fc015a3"
+  integrity sha512-uGdSIu1nk3kej2iZsLyDoJ7e9bnPzIgY0naW/HdknGj61zScaprVEVGHrPoXqI+M9sP0NDnTK2jpkvmldpuqDw==
   optionalDependencies:
     clipboard "^2.0.0"