[css-cascade-5] Minor clean-up of revert-level:

* Add to 'all' shorthand propdef
* Remove resolved issue
* Cross-link to definition of layers
* Shift informative statement into a note

Author: fantasai

css-cascade-5/Overview.bs

@@ -406,7 +406,7 @@ Resetting All Properties: the 'all' property</h3>
 
 	<pre class="propdef shorthand">
 	Name: all
-	Value: initial | inherit | unset | revert
+	Value: initial | inherit | unset | revert | revert-layer
 	</pre>
 
 	The 'all' property is a <a>shorthand</a>
@@ -1126,7 +1126,7 @@ Cascade Layers</h3>
 
 	In the same way that [=cascade origins=] provide a balance of power
 	between user and author styles,
-	<dfn export>cascade layers</dfn> provide a structured way
+	<dfn export local-lt="layer">cascade layers</dfn> provide a structured way
 	to organize and balance concerns within a single origin.
 	Authors can create layers to represent element defaults,
 	third-party libraries, themes, components,
@@ -1159,8 +1159,6 @@ Cascade Layers</h3>
 		and come first in the source order.
 	</div>
 
-	Issue(w3c/csswg-drafts#5793): Do we need a keyword similar to `revert`, but for cascade layers?
-
 <h4 id="at-layer">
 Declaring Cascade Layers: the ''@layer'' rule</h4>
 
@@ -1542,14 +1540,15 @@ Rolling Back Cascade Origins: the ''revert'' keyword</h4>
 Rolling Back Cascade Layers: the ''revert-layer'' keyword</h4>
 
 	If the <a>cascaded value</a> of a property is the <dfn for=all>''revert-layer''</dfn> keyword,
-	the <a>cascaded value</a> is rolled back to the layer below,
+	the <a>cascaded value</a> is rolled back to the [=layer=] below,
 	so that the <a>specified value</a> is calculated
-	as if no rules were specified in the current layer
+	as if no rules were specified in the current [=cascade layer=]
 	for this property on this element.
-	If there are no lower-priority layers in the same [=cascade origin=]
-	as the ''revert-layer'' value,
-	the <a>cascaded value</a> may be rolled back to a previous origin,
-	as defined by the [=revert=] keyword.
+
+	Note: If there are no lower-priority layers
+	in the same [=cascade origin=] as the ''revert-layer'' value,
+	the <a>cascaded value</a> will roll back to the previous origin,
+	just as for the [=revert=] keyword.
 
 
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