[cleanup] Consistent spelling as nonwetting/Nonwetting

exercises/exercise-basic/injection2p2cproblem.hh

@@ -217,7 +217,7 @@ public:
 
         // note that because we start with a single phase system the primary variables
         // are pl and x^w_N2. This will switch as soon after we start injecting to a two
-        // phase system so the primary variables will be pl and Sn (non-wetting saturation).
+        // phase system so the primary variables will be pl and Sn (nonwetting saturation).
         values[Indices::pressureIdx] = pw;
         values[Indices::switchIdx] = moleFracLiquidN2;