Add project: mkdocs-note

**What kind of change does this PR introduce?** <!-- (Update "[ ]" to "[x]" to check a box) --> - [x] Add a project - [ ] Update a project - [ ] Remove a project - [ ] Add or update a category - [ ] Change configuration - [ ] Documentation - [ ] Other, please describe: **Description:** <!--- Use this section to describe your changes. We recommend only to add, update, or remove one project per pull request. If your PR adds a new project, just put the project name and a short description of the project here.--> **Checklist:** <!--- Before you submit the PR, go over this checklist and make sure you can tick off all the boxes. [] -> [x] --> - [x] I have read the [CONTRIBUTING](https://github.com/best-of-lists/best-of/blob/main/CONTRIBUTING.md) guidelines. - [x] I have not modified the `README.md` file. Projects are only supposed to be added or updated within the `projects.yaml` file since the `README.md` file is automatically generated.