text: Title: Add roadmap link to the README
  Body: It would be good to see a link to our [roadmap](https://wagtail.org/roadmap/) in the readme. While we're at it it may make sense to make the words 'release notes' into a link to our [docs releases](https://docs.wagtail.org/en/stable/releases/index.html) page. 
  
  https://github.com/wagtail/wagtail/blob/912c0881f9bf17adb03a8c7fe83ab36c969b0521/README.md?plain=1#L73
  
  ![Screenshot_20241010-221231](https://github.com/user-attachments/assets/34445560-8e22-460e-b40d-c7ebb4f862ea)
  