Update README.md

Author: quickwritereader

README.md

@@ -78,9 +78,12 @@ Please read GotoBLAS_01Readme.txt
 - **ARM Cortex-A57**: Experimental
 
 #### IBM zEnterprise System:
-- **Z13**: Double precision real number
-    git checkout z13
-    make USE_TRMM=1
+- **Z13**: blas3 for double
+```
+     git checkout z13  
+     make USE_TRMM=1 
+```     
+     
 
 ### Support OS:
 - **GNU/Linux**