Update mkdocs-markdownextradata-plugin requirement

Updates the requirements on [mkdocs-markdownextradata-plugin](https://github.com/rosscdh/mkdocs-markdownextradata-plugin) to permit the latest version.
- [Release notes](https://github.com/rosscdh/mkdocs-markdownextradata-plugin/releases)
- [Commits](rosscdh/mkdocs-markdownextradata-plugin@0.1.7...0.2.6)

---
updated-dependencies:
- dependency-name: mkdocs-markdownextradata-plugin
  dependency-version: 0.2.6
  dependency-type: direct:production
...

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

Author: dependabot[bot]

requirements-docs.txt

@@ -1,6 +1,6 @@
 markdown-include
 mdx-include >=1.4.1,<2.0.0
 mkdocs >=1.1.2,<2.0.0
-mkdocs-markdownextradata-plugin >=0.1.7,<0.3.0
+mkdocs-markdownextradata-plugin >=0.2.6,<0.3.0
 mkdocs-material
 mkdocstrings