Update README.rst

Changed t, pt to math mode.

examples/distgen/README.rst

@@ -71,7 +71,7 @@ We run the following script to analyze correctness:
 A Kapchinskij-Vladimirskij (K-V) distribution
 ===============================================
 
-A 4D K-V distribution in the transverse phase space variables ( + a longitudinally uniform distribution in t + a Gaussian distribution in p_t ).
+A 4D K-V distribution in the transverse phase space variables ( + a longitudinally uniform distribution in :math:`t` + a Gaussian distribution in :math:`p_t` ).
 
 In this test, the initial and final values of :math:`\lambda_x`, :math:`\lambda_y`, :math:`\lambda_t`, :math:`\epsilon_x`, :math:`\epsilon_y`, and :math:`\epsilon_t` must agree with nominal values.
 
@@ -169,7 +169,7 @@ We run the following script to analyze correctness:
 A 4D Kurth Distribution
 ============================
 
-A 4D Kurth distribution in the transverse phase space variables ( + a longitudinally uniform distribution in t + a Gaussian distribution in p_t ).
+A 4D Kurth distribution in the transverse phase space variables ( + a longitudinally uniform distribution in :math:`t` + a Gaussian distribution in :math:`p_t` ).
 
 
 In this test, the initial and final values of :math:`\lambda_x`, :math:`\lambda_y`, :math:`\lambda_t`, :math:`\epsilon_x`, :math:`\epsilon_y`, and :math:`\epsilon_t` must agree with nominal values.