fix definition

Caught by Bruno

spec/doc.tex

@@ -2333,7 +2333,7 @@ with $1 \leq k \leq n$.
     \begin{plList}
       \Gamma\proofsep&
       i.& \operatorname{ite} \varphi_1\;\varphi_2\;\varphi_3 \leftrightarrow
-      (\varphi_1 \rightarrow \varphi_2) \land (\neg\varphi_1 \rightarrow \neg\varphi_3)
+      (\varphi_1 \rightarrow \varphi_2) \land (\neg\varphi_1 \rightarrow \varphi_3)
       &(\currule)\\
     \end{plList}
   \end{plContainer}