[css-counter-styles] Set the ethiopic-numeric suffix to a space, per fantasai's conversation with some Ethiopians.

Author: tabatkins

css-counter-styles/Overview.bs

@@ -2398,6 +2398,7 @@ Ethiopic Numeric Counter Style: ''ethiopic-numeric''</h3>
 
 	For this system, the name is "ethiopic-numeric",
 	the 'range' is ''1 infinite'',
+	the 'suffix' is a single space (U+0020) character,
 	and the rest of the descriptors have their initial value.
 
 	<div class="example">