Add note to system notes that are only visible to project members
See https://gitlab.com/gitlab-org/gitlab-ce/issues/59386 for context.
To summarize, GitLab shows system notes only for members that have access to the project that generates the system notes. However, from a member perspective they don't know that it's only visible by them, so panic ensues :)
It would be useful to add some text explaining that it's only visible to them. For example, in this case:
Mark can see the system note but I cannot. It would be useful to put in the system note a text such as "only visible by members with access" or a (?) icon with that explanation.