set code blocks to eval=FALSE for tissue gene expression library

Author: smcclatchy

episodes/clustering.Rmd

@@ -20,7 +20,7 @@ exercises: 30
 
 We will demonstrate the concepts and code needed to perform clustering analysis with the tissue gene expression data:
 
-```{r}
+```{r, eval=FALSE}
 library(tissuesGeneExpression)
 data(tissuesGeneExpression)
 ```

episodes/cross-validation.Rmd

@@ -38,7 +38,7 @@ seen how this leads to over-fitting.
 
 Let's start by loading the tissue gene expression dataset:
 
-```{r}
+```{r, eval=FALSE}
 library(tissuesGeneExpression)
 data(tissuesGeneExpression)
 ```