In our workflow I have added a property key of jira.issue.editable to the last several statuses in our workflow, and set it to false. This locks the card once it reaches a certain point so it cannot be edited.
I also need to do this for comments. Folks should be able to add comments whenever, but only edit them when they are in statuses in the first half of the workflow. I thought there would be a similar permission for editing documents, but I can't find it.
Interestingly, on the API page (https://docs.atlassian.com/software/jira/docs/api/7.13.1/com/atlassian/jira/security/Permissions.html) it looks like there used to be a permission called "edit_own_comments" but it sounds like its deprecated, which I find odd. I also am not sure what the full permission designation would be. I tried jira.edit_own_comments but this didn't work.