To address these issues, we will have multiple versions of the documentation. Each documentation page will have a version switcher as shown below.
Version specific documentation is now live on https://docs.erpnext.com/
I, @prasadr, and @ambareen have been working on v13 screenshots and few modules have already been updated. All the remaining module screenshots will be updated by 30-June-2021.
Will shortly update the guidelines for sending PRs.