Updated Automattic/vip-go-mu-plugins pull request template

Since the changelog generation is now automated, we’ve made some changes to the pull request template to reflect that. We removed links to pull requests from the examples since they’re no longer needed and edited the changelog checklist item to be inclusive. The expectation is that everyone fills out a proper changelog description and this is now reflected properly in the pull request template.

https://github.com/Automattic/vip-go-mu-plugins/pull/1953