added -s documentation

README.md

@@ -15,7 +15,8 @@ set an env variable for $EDITOR and/or $VISUAL in .bashrc
     export EDITOR=vi
     export VISUAL=geany
 
-## Usage
+## Usage:
+
 `skratch` creates a random file in .skratch and opens it in the EDITOR
 
 `<filename>` opens or creates a file with a specific name in ~/.skratch
@@ -24,4 +25,6 @@ set an env variable for $EDITOR and/or $VISUAL in .bashrc
 
 `-l` lists files in ~/.skratch
 
+`-s` adds a suffix to the file
+
 `-v` uses the VISUAL editor