fix error in equation for maximum number of bound states

Author: PaulWAyers

book/HOandMorse.ipynb

@@ -674,7 +674,7 @@
     "The number of states can be computed relatively easily using the equation\n",
     "\n",
     "$$\n",
-    "k_{\\max} = \\left\\lfloor \\frac{2D_e}{\\hbar \\omega_0} - 1 \\right\\rfloor\n",
+    "k_{\\max} = \\left\\lfloor \\frac{2D_e}{\\hbar \\omega_0} - \\tfrac{1}{2} \\right\\rfloor\n",
     "$$\n",
     "\n",
     "The zero-point energy of the Morse oscillator can be written as a correction to the zero-point energy of the harmonic oscillator. Specifically, using\n",