Document more quantities in polytropic EOS

src/PointwiseFunctions/Hydro/EquationsOfState/PolytropicFluid.hpp

@@ -34,12 +34,15 @@ namespace EquationsOfState {
  * polytropic exponent is related to the polytropic index \f$N_p\f$ by
  * \f$N_p=1/(\Gamma-1)\f$.
  *
- * \f{align}
- * \epsilon&=\frac{K}{\Gamma-1}\rho^{\Gamma-1} \\
+ * We also have
+ *
+ * \f{align}{
+ * \epsilon&=\frac{K\rho^{\Gamma-1}}{\Gamma-1}\\
  * h&=1+\epsilon+\frac{p}{\rho}=1+\frac{K\Gamma}{\Gamma-1}\rho^{\Gamma-1} \\
+ * T&=0 \\
  * c_s^2&=\frac{\Gamma p}{\rho h}
- *       =\frac{\Gamma(\Gamma-1)p}{\rho(\Gamma-1)+\Gamma p}
- *       =\left(\frac{1}{K\Gamma\rho^{\Gamma-1}}+\frac{1}{\Gamma-1}\right)^{-1}
+ * =\frac{\Gamma(\Gamma-1)p}{\rho(\Gamma-1)+\Gamma p}
+ * =\left(\frac{1}{\Gamma K\rho^{\Gamma-1}}+\frac{1}{\Gamma-1}\right)^{-1}
  * \f}
  */
 template <bool IsRelativistic>