Caution that roles should start with ROLE_

In order to save someone else a few hours of frustration make it clear that the ROLE_ preface is not just for show.
Add formatting, links, and clarity
Add label book-security-roles
Fix reference label
minor #4218 Caution that roles should start with ROLE_ (jrjohnson)

This PR was merged into the 2.3 branch.

Discussion
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Caution that roles should start with ROLE_

In order to save someone else a few hours of frustration make it clear that the ROLE_ preface is not just for show.

| Q             | A
| ------------- | ---
| Doc fix?      | yes
| New docs?     | no
| Applies to    | all
| Fixed tickets |

Commits
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749996b Fix reference label
f856641 Add label book-security-roles
9d13930 Add formatting, links, and clarity
1522de7 Caution that roles should start with ROLE_