Update docs/labwc-config.5.scd

Co-authored-by: Andrew J. Hesford <ajh@sideband.org>

docs/labwc-config.5.scd

@@ -98,10 +98,24 @@ Configuration must be wrapped in a <labwc_config> root-element like this:
 
 *labwc* parses XML in an element/attribute agnostic way. This is a design
 decision to increase config file flexibility and keep code simple. In practical
-terms, this means that `<a><b>c</b></a>` is equivalent to `<a b="c" />`.
+terms, this means that `<a><b>c</b></a>` is usually equivalent to `<a b="c" />`.
+However, there are some caveats:
+- In menu.xml, the attributes `id` and `label` *must* be expressed as attributes
+  rather than as separate child tags.
+- Ordering of attributes can sometimes be singificant. For example, when setting
+  fonts via attributes rather than children,
   
-Note: This does not apply to all aspects of menu.xml, specifically the
+      <font place="ActiveWindow" name="..." size="..." />
-attributes id, label and execute.
+
+  will set a font for active window titles, while
+  
+       <font name="..." size="..." place="ActiveWindow" />
+       
+  will set a font as if `place` were unspecified, because `name` and `size` will be
+  processed before `place`.
+  
+In general, it is recommended that attributes not be used to collapse more than
+one level of the configuration hierarchy.
 
 The following three are therefore treated the same: