minor #7230 Update file_permissions.rst (beyerz, javiereguiluz)

This PR was submitted for the 3.2 branch but it was merged into the 2.7 branch instead (closes #7230).

Discussion
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Update file_permissions.rst

Added extra explanation for setfacl to clarify the purpose of each command

Commits
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56746dc Minor fix and rewording
b0e109d Update file_permissions.rst

Author: xabbuh

setup/file_permissions.rst

@@ -55,8 +55,13 @@ following script to determine your web server user and grant the needed permissi
 
 .. note::
 
-    setfacl isn't available on NFS mount points. However, storing cache and logs
-    over NFS is strongly discouraged for performance reasons.
+    The first ``setfacl`` command sets permissions on the existing files and
+    folders, while the second one sets permissions for future files and folders.
+    Both of these commands assign permissions for the system user and the Apache 
+    user.
+
+    ``setfacl`` isn't available on NFS mount points. However, storing cache and
+    logs over NFS is strongly discouraged for performance reasons.
 
 4. Without Using ACL
 ~~~~~~~~~~~~~~~~~~~~