expand stated armour rules

rules/armour.tex

-Armour provides \gls{dr}, which can protect against Damage, but only covers a few numbers on the dice.
+Armour reduces Damage, but only covers some parts of the body.
+The more \gls{dr} the armour has, the more Damage it takes away, and the more armour the character wears, the more dice-results will be covered by the armour. 
 
 \begin{itemize}
   \item
@@ -9,4 +10,6 @@ Armour provides \gls{dr}, which can protect against Damage, but only covers a fe
   Similarly, \glspl{pc} rolling over an opponent's Attack score, and \emph{then} above their armour's \textit{Covering}, ignore all \gls{dr} as their weapon finds bare flesh.
   \item
   Full armour can provide more covering.
+  \item
+  \Glspl{fp} apply only after \gls{dr}.
 \end{itemize}