minor #3547 Update acl.rst (iqfoundry)

This PR was submitted for the master branch but it was merged into the 2.3 branch instead (closes #3547).

Discussion
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Update acl.rst

| Q             | A
| ------------- | ---
| Doc fix?      | yes
| New docs?     | no
| Applies to    | current
| Fixed tickets |
ACE is not defined in the scope of this document, hopefully this adds some clarity.

Commits
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cee5b9d Update acl.rst
37f49e3 Update acl.rst

cookbook/security/acl.rst

@@ -90,6 +90,10 @@ Getting Started
 Coming back to the small example from the beginning, you can now implement
 ACL for it.
 
+Once the ACL is created, you can grant access to objects by creating an
+Access Control Entity (ACE) to solidify the relationship between the entity
+and your user.
+
 Creating an ACL, and adding an ACE
 ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~