README: Change incorrect file extension scss->sass

Change in the SASS example:
// scss/main.scss
to
// sass/main.sass
Since the folder structure given above clearly states that sass/main.sass is to be edited

1 files changed, 1 insertions, 1 deletions

diff --git a/README.md b/README.md
index bff807b..740ba87 100644
--- a/README.md
+++ b/README.md
@@ -164,7 +164,7 @@ project/
 #### Input
 
 ```sass
-// scss/main.scss
+// sass/main.sass
 
 @import "../node_modules/rfs/sass"