Add a favicon to the documentation

[julien-deramond]

Description

Our documentation doesn't have any favicon files for now.

To close this issue, a favicon file (or files) should be added to all pages of the documentation.

There could be extra things to do for https://ods-charts.netlify.app/api/.

Don't forget to add the favicon file (or files) to our https://github.com/Orange-OpenSource/ods-charts/blob/main/NOTICE.txt.

Sub-tasks

• Add favicons images in the repository and mention them in a NOTICE.txt
• Add favicons to the documentation
• Add favicons to the /api (we might need something like https://www.npmjs.com/package/typedoc-plugin-extras as an extra plugin to do that)