[INGI1123] Fix line break in APE

src/q6/calcu-INGI1123/exercises/calcu_tp5.tex

@@ -137,6 +137,7 @@ We recall the definition of \(K\):
 \(K = \{i : \phi_i(i) \textnormal{ halts}\}\).
 Assume \(K\) is recursive.
 We can then define a function
+
 \[
 f(x) = \begin{cases} c \in \bar{K}\,, & \textnormal{ if } x \in K\,,\\
 d \in K\,, & \textnormal{ if } x \in \bar{K}\,. \end{cases}