releases link when update available

**Describe the problem you have/What new integration you would like**

i would like a link added to the release url when esphome dashboard has a new version available

**Please describe your use case for this integration and alternatives you've tried:**

i see 'update available' for my esphgome devices but i have to manually go to the repo and releases to see what the update is about. it would be nice for the 'update available' text to be a link to the releases page so i can easily see what changes there are before updating

**Additional context**

if someone can point me to the correct file i can open a PR for this