backwards_ecal: fix ylim top for resolution

benchmarks/backwards_ecal/backwards_ecal.org

@@ -225,6 +225,7 @@ plt.fill_between(
     np.sqrt((2 / np.sqrt(energy_values)) ** 2 + 3 ** 2),
     alpha=0.2, color="black", label=r"YR requirement $2\% / \sqrt{E} \oplus (1-3)\%$",
 )
+plt.ylim(top=10.)
 plt.legend()
 plt.xlabel("Energy, GeV", loc="right")
 plt.ylabel(r"$\sigma_{E} / E$ derived from FWHM, %", loc="top")