Update INTRO.ipynb

Typo correction

Author: bjlittle

INTRO.ipynb

@@ -10,7 +10,7 @@
     "\n",
     "Whilst this is not the only use for the ``stratify`` package, NWP vertical interpolation was the motivating usecase for the package's creation.\n",
     "\n",
-    "In its simplest form, vertical interpolation ammounts to a 1d interpolation at each grid-point. Whilst some more sophistication exists for a number of interpolators, ``stratify`` can be seen as an optimisation to vectorize these interpolations beyond naïve nested for-loops.\n",
+    "In its simplest form, vertical interpolation amounts to a 1d interpolation at each grid-point. Whilst some more sophistication exists for a number of interpolators, ``stratify`` can be seen as an optimisation to vectorize these interpolations beyond naïve nested for-loops.\n",
     "\n",
     "#### Data setup\n",
     "In order to setup the problem, let's manufacture some reasonably realistic NWP data.\n",