docs: FC0006 exclude AccessByPermission (#155)

Document that the AccessByPermission property is not covered by FC0006:
it shares the Permissions syntax but is a UI-visibility mask with no
direct/indirect distinction, and uppercase is its documented form.

Co-authored-by: Claude Fable 5 <noreply@anthropic.com>

Author: Arthurvdv

content/docs/analyzers/FormattingCop/FC0006.md

@@ -56,6 +56,27 @@ permissionset 50100 "Sales Documents"
 
 The `InherentPermissions` property is also excluded for the same reason.
 
+The `AccessByPermission` property is not covered either. Although it uses the same syntax as
+`Permissions`, it is a UI-visibility mask: it hides a table field, page field, page part, action
+or object from users who lack the listed permission. It grants nothing, so it has no direct/indirect
+distinction, and Microsoft Learn documents the uppercase form as its canonical spelling.
+
+{{< highlight al "hl_lines=9" >}}
+page 50100 "Sales Order Extras"
+{
+    actions
+    {
+        area(Processing)
+        {
+            action("BOM Level")
+            {
+                AccessByPermission = tabledata "BOM Buffer" = R;
+            }
+        }
+    }
+}
+{{< /highlight >}}
+
 ### Code fix
 
 The **ALCops: Convert permission values to lowercase** code fix converts every permission value in the `Permissions` property to lowercase, preserving entry order and formatting.