Connect the to-do page to the platform one

[libremente]

Is your feature request related to a problem? Please describe.

Right now there is no explicit way of knowing which open issues are there starting from the platform page.

Describe the solution you'd like

I would like to see a clear indication of which issues are open foreach platform.

Describe alternatives you've considered

Several options.

1. see a counter of all the open issues in the /platform page, an overview is always interesting.
2. then, once we get inside a page we need a clear indication of the issue.
   2a) for the MVP it's OK to just have the number of the open issues and the link to the /to-do page.
   2b) this implies slightly changing the https://developers.italia.it/it/cosa-fare page to accept anchor in the URL, something like /cosa-fare?platform=<platform_name> or similar
3. for the next version we can have directly the filter applied at the end of each platform page:

This should make the developer experience more interesting!

Additional context