Revert "Fix typo chapter 8"

This reverts commit f1c3528.

topofeatures/topofeatures.tex

@@ -327,13 +327,13 @@ \subsection{Peak}
 that is one point that happens to be a few centimetres higher than all its neighbours would be classified as a peak (the small terrain in Figure~\ref{fig:feature_points} contains several peaks), while if we consider a hill we would surely consider only the top as the peak.
 A peak is therefore on the scale of the data.
 
-The contour line through $p$ does not exist.
+The contour line through the $p$ does not exist.
 
 %%%
 \subsection{Pit}
 A point $p$ whose surrounding is formed only of points that are of higher elevation is a pit.
 The same remarks as for peak apply here.
-The contour line through $p$ does not exist.
+The contour line through the $p$ does not exist.
 
 %%%
 \subsection{Saddle point}%