doc: correct confluence status role example

The Confluence Status macro role example did not have a proper example
when hinting the use of brackets for the alternative style. This commit
corrects the example to follow the description of the alternative style
for this role.

Signed-off-by: James Knight <[email protected]>

Author: jdknight

doc/roles.rst

@@ -154,7 +154,7 @@ generated Confluence documents.
 
     .. code-block:: rst
 
-        :confluence_status:`PASSED <green>`
+        :confluence_status:`PASSED [green]`
 
 
 .. references ------------------------------------------------------------------