make resting actions always turn a die

rules/actions_resting.tex

@@ -2,5 +2,6 @@
 
 \begin{itemize}
   \item
-  When characters can try something again and again, set one die to a '6' and roll as normal.
+  When characters can try something again and again, set the darker of their dice to a `6'.
+  If this roll still fails, the action can never succeed.
 \end{itemize}