[css-cascade-5] bikeshed fix

Author: fantasai

css-cascade-5/Overview.bs

@@ -1860,7 +1860,7 @@ Erasing All Declarations: the ''unset'' keyword</h4>
 <h4 id="default" for=all caniuse="css-revert-value">
 Rolling Back Cascade Origins: the ''revert'' keyword</h4>
 
-	The <dfn value>revert</dfn> [=CSS-wide keyword=]
+	The <dfn value for=all>revert</dfn> [=CSS-wide keyword=]
 	rolls back the cascade to the [=cascaded value=] of the earlier [=origin=].
 
 	If the <a>cascaded value</a> of a property is