add fatigue travel notes to index

rules/fatigue.tex

@@ -3,6 +3,8 @@
   Every strenuous activity inflicts one \gls{fatigue}.
   \begin{itemize}
     \item
+    \index{Marching}
+    \index{Travel}
     Marching through a mile of forest inflicts \pgls{fatigue}.
     \item
     Marching along two miles of road inflicts \pgls{fatigue}.