Update heterogeneity.md

doc/heterogeneity.md

@@ -41,6 +41,6 @@ From the output of `prepare_protein_library`, we see that there are 3 heterogene
 
 Now, we have a variety of heterogeneity models. In general, there are four ways to assess a model: estimate the sampling precision, compare the model to data used to construct it, validate the model against data not used to construct it, and quantify the precision of the model. Here, we will focus specifically on comparing the model to experimental data, as other assessments will be performed later, when the [trajectory models are assessed.] (@ref trajectory_assess)
 
-In the `Heterogeneity/Heterogeneity_Assessment` folder, there is a single script, `plot_heterogeneity.m`. This script plots the modeled and experimental copy numbers simultaneously. From these plots, we observe that the range of possible experimental copy numbers are well sampled by the heterogeneity models, indicating that we are prepared for [snapshot modeling] (@ref snapshots)
+In the `Heterogeneity/Heterogeneity_Assessment` folder, there is a single script, `plot_heterogeneity.m`. This script plots the modeled and experimental copy numbers simultaneously, as shown below for proteins A (a), B (b), and C (c). From these plots, we observe that the range of possible experimental copy numbers are well sampled by the heterogeneity models, indicating that we are prepared for [snapshot modeling] (@ref snapshots)
 
 \image html Heterogeneity_Assessment.png width=600px