[css-anchor-position] Allow applying try-tactic to a named try block, for simplicity

Author: tabatkins

css-anchor-position-1/Overview.bs

@@ -1002,7 +1002,7 @@ Giving Fallback Options: the 'position-try-options' property {#position-try-opti
 
 <pre class=propdef>
 Name: position-try-options
-Value: none | [ <<dashed-ident>> | <<try-tactic>> ]#
+Value: none | [ <<dashed-ident>> || <<try-tactic>> ]#
 Initial: none
 Inherited: no
 Applies to: [=absolutely-positioned=] elements
@@ -1082,6 +1082,18 @@ Values have the following meanings:
 		anchor(top) becomes anchor(bottom);
 		start becomes end;
 		etc.
+
+	: <dfn><<dashed-ident>> || <<try-tactic>></dfn>
+	::
+		Combines the effects of the previous two options:
+		if there is a ''@position-try'' rule
+		with the given name,
+		then applies its [=position option=] to the element's base style,
+		transforms it according to the specified <<try-tactic>>,
+		and then adds the result
+		to the element's [=position options list=].
+
+		Otherwise, does nothing.
 </dl>