Update widget list for other projects in README
First of all thank you for all the work you've put into this library!
That said, the list of widgets used by other projects given at the end of the README. In particular, I was searching for examples of how to implement the HdyLeaflet, and I realized that the following projects used it despite not being mentionned:
- Fractal
- GNOME Contacts
Giving us that list was a great idea though, thank you for that.