Bump dompurify from 2.4.7 to 2.5.6 in /docs

Bumps [dompurify](https://github.com/cure53/DOMPurify) from 2.4.7 to 2.5.6.
- [Release notes](https://github.com/cure53/DOMPurify/releases)
- [Commits](cure53/DOMPurify@2.4.7...2.5.6)

---
updated-dependencies:
- dependency-name: dompurify
  dependency-type: indirect
...

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

docs/yarn.lock

@@ -833,9 +833,9 @@ domhandler@^4.0.0, domhandler@^4.2.0, domhandler@^4.3.1:
     domelementtype "^2.2.0"
 
 dompurify@^2.2.8:
-  version "2.4.7"
-  resolved "https://registry.yarnpkg.com/dompurify/-/dompurify-2.4.7.tgz#277adeb40a2c84be2d42a8bcd45f582bfa4d0cfc"
-  integrity sha512-kxxKlPEDa6Nc5WJi+qRgPbOAbgTpSULL+vI3NUXsZMlkJxTqYI9wg5ZTay2sFrdZRWHPWNi+EdAhcJf81WtoMQ==
+  version "2.5.6"
+  resolved "https://registry.yarnpkg.com/dompurify/-/dompurify-2.5.6.tgz#8402b501611eaa7fb3786072297fcbe2787f8592"
+  integrity sha512-zUTaUBO8pY4+iJMPE1B9XlO2tXVYIcEA4SNGtvDELzTSCQO7RzH+j7S180BmhmJId78lqGU2z19vgVx2Sxs/PQ==
 
 domutils@^2.5.2, domutils@^2.8.0:
   version "2.8.0"