Update contributing.md

Co-authored-by: Marks Polakovs <[email protected]>

docs/contributing.md

@@ -4,6 +4,12 @@
 
 We use [Linear](https://linear.app/ystv) to track issues - to access it, sign in with your @ystv.co.uk Google account (ask a Computing Team member if you don't have one).
 
+File an issue for any significant change you plan to make, particularly if it was requested by someone outside of Computing Team (in this case, please add the `User Feedback` label).
+
+If you're planning to work on something, please assign it to yourself on Linear. If you need to stop work, or you find it's too complicated, un-assign it (and leave a comment summarising your progress so far).
+
+Feel free to assign any un-assigned issue to yourself, you don't need to ask anyone. But if the issue is assigned to someone else, ask them before you start work on it.
+
 ## Branch Names
 
 Branches created for Linear issues should use the branch name [provided by linear](https://linear.app/docs/github#link-using-pull-requests) which follow the format `int-<issue id>-<issue title>`. Branches unrelated to a filed issue should be in the format `<initials or first name>/<feature or fix being implemented>`, for example `mia/fix-main-again`.