Update README.md

Add perm pvalues tutorial

Author: JEFworks

README.md

@@ -12,9 +12,9 @@ The `liger` package provides a lightweight R implementation of this enrichment t
 
 # Tutorials
 - **[Gene Set Enrichment Analysis with LIGER](vignettes/gsea.pdf)**  
-- **[Highlighting the power of gene set enrichment analysis using simulation](vignettes/simulation.pdf)**  
 - **[Interpreting Enrichment Scores and Edge Values](vignettes/interpreting.pdf)**  
-
+- **[Exploring Permutation P-values](vignettes/permpvals.pdf)**
+- **[Highlighting the power of gene set enrichment analysis using simulation](vignettes/simulation.pdf)**  
 
 # Sample plots