Rephrase critical error value; expand cetrig note

From Ved's feedback on the PR.

xml/core_registers.xml

@@ -76,7 +76,7 @@ same project unless stated otherwise.
             more specific halt reason than "other." Otherwise it contains 0.
 
             <value v="0" name="critical error">
-                The hart entered a critical error state. Part of the
+                The hart entered a critical error state, as defined in the
                 ((Smdbltrp)) extension.
             </value>
 
@@ -106,9 +106,13 @@ same project unless stated otherwise.
 
             [NOTE]
             ====
-                When {dcsr-cetrig} is enabled, resuming from Debug Mode
+                When {dcsr-cetrig} is 1, resuming from Debug Mode
                 following an entry due to a critical error will result in an
                 immediate re-entry into Debug Mode due to the critical error.
+                The debugger may resume with {dcsr-cetrig} set to 0 to allow the
+                platform defined actions on critical-error signal to occur.
+                Other possible actions include initiating a hart or platform
+                reset using the Debug Module reset control.
             ====
         </field>
         <field name="0" bits="18" access="R" reset="0" />