write measurements header

traits.tex

 \chapter{Measurements}
 \index{Traits}
 
+We measure characters with three Primary Traits: their natural `Attributes', the `Skills' they've learnt, and specialized `Knacks'.
+All of the derived Traits come from these three.%
+\footnote{
+  You're not planning on reading this thing, are you?
+  It's a reference book, so it's just here for reference.
+  If you're a player, grab yourself a copy of the book of \textit{Stories}.
+  If you're a \gls{gm}, start with an adventure module, then print a copy of the book of \textit{Judgement}.
+}
+
 \section{Attributes}
 \label{randomAttributes}