Added README for Michel analysis

michel-decay/README.md

+# Michel decays $`L\to \nu\bar\nu l`$
+
+References: [[1909.10244]](https://arxiv.org/abs/1909.10244), [[1811.06461]](https://arxiv.org/abs/1811.06461), MSc thesis of A. Gurgone
+
+Configurations implemented
+
+ * No cuts to obtain decay rate
+ * Demonstration cuts: no photons with $`E_\gamma > 10\,{\rm MeV}`$
+   within a cone of $`|\cos\sphericalangle(\vec p_\gamma,\vec p_e)| > 0.8`$
+ * MEG cuts with photon veto
+ * Full reconstruction of
+```math
+\frac{{\rm d}^2\Gamma}{{\rm d}E_e\,{\rm d}(\cos\theta)} =
+\Gamma_0(f(E_e)+P\,\cos\theta\ g(E_e))
+```