Add the description of "Confluence Administrator can't change System Administrator's password" in CAC Global Permission Overview doc.

Issue Summary

System Administrator has stronger primiledge than Confluence Administrator, it is mentioned in Global Permissions Overview but it is indirectly.

The description of "Confluence Administrator can't change System Administrator's password" should be written in Global Permissions Overview directly.

This is reproducible on Data Center: yes

Suggestion

Make the description of "Confluence Administrator can't change System Administrator's password" in Global Permissions Overview doc.

Actual Results

There is no description about "Confluence Administrator can't change System Administrator's password".