Fix GitHub pages theme config (#5450)

* Render meaningful repo files as pages

In README.md there are a link to CONTRIBUTING.md that doesn't work as github pages so configure to include some of this meaningful files present in repo.

* Enable relative link collections

Referenced Doc:
- https://github.com/benbalter/jekyll-relative-links#processing-collections
- https://github.com/nicolas-van/easy-markdown-to-github-pages#create-the-_configyml-file

_config.yml

 theme: jekyll-theme-minimal
 plugins:
   - jemoji
+  - jekyll-relative-links
+relative_links:
+  enabled: true
+  collections: true
+include:
+  - CONTRIBUTING.md
+  - LICENSE.md
+  - CODE_OF_CONDUCT.md
+