[css-counter-styles-3] Clarify that speak-as represents spoken output. It may be used for other AT. w3c#6040

Author: fantasai

css-counter-styles-3/Overview.bs

@@ -1113,8 +1113,10 @@ Speech Synthesis: the '@counter-style/speak-as' descriptor</h3>
 
 	A counter style can be constructed with a meaning that is obvious visually,
 	but impossible to meaningfully represent via a speech synthesizer or other non-visual means,
-	or possible but nonsensical when naively transformed.
+	or possible but nonsensical when naively read out loud.
 	The '@counter-style/speak-as' descriptor describes how to synthesize the spoken form of a counter formatted with the given counter style.
+	Assistive technologies should use this spoken form when reading out the counter style,
+	and may use the 'speak-as' value to inform transformations to outputs other than speech.
 	Values have the following meanings:
 
 	<dl dfn-for="@counter-style/speak-as" dfn-type=value>
@@ -1166,9 +1168,6 @@ Speech Synthesis: the '@counter-style/speak-as' descriptor</h3>
 			for the counter styles participating in the loop.
 	</dl>
 
-	Note: The values above are defined by referring to "speaking" a value,
-	but should be understand as referring to any non-visual means of representing text.
-
 	<div class='example'>
 		The ability to defer pronunciation to another counter style can help when the symbols being used aren't actually letters.
 		For example, here's a possible definition of a ''circled-lower-latin'' counter-style, using some special Unicode characters: