Part: fix source comment typo

src/Mod/Part/App/FeatureExtrusion.cpp

@@ -222,7 +222,7 @@ Base::Vector3d Extrusion::calculateShapeNormal(const App::PropertyLink& shapeLin
     GeomAdaptor_Surface surf(planeFinder.Surface());
     gp_Dir normal = surf.Plane().Axis().Direction();
 
-    //now se know the plane. But if there are faces, the
+    //now we know the plane. But if there are faces, the
     //plane normal direction is not dependent on face orientation (because findPlane only uses edges).
     //let's fix that.
     TopExp_Explorer ex(sh, TopAbs_FACE);