Move 'assets/sass' -> 'assets/scss'

We don't use SASS so this was misleading.

Signed-off-by: Piotr Bocheński <bochenski.piotr@gmail.com>

layouts/partials/head.html

@@ -8,6 +8,6 @@
     <link rel="stylesheet" href="https://fonts.googleapis.com/icon?family=Material+Icons" />
     <link rel="stylesheet" href="https://cdnjs.cloudflare.com/ajax/libs/font-awesome/5.15.3/css/all.min.css" integrity="sha512-iBBXm8fW90+nuLcSKlbmrPcLa0OT92xO1BIsZ+ywDWZCvqsWgccV3gFoRBv0z+8dLJgyAHIhR35VZc2oM/gI1w==" crossorigin="anonymous" referrerpolicy="no-referrer" />
 
-    {{- $style := resources.Get "sass/main.scss" | resources.ExecuteAsTemplate "style.main.scss" . | toCSS | minify | fingerprint }}
+    {{- $style := resources.Get "scss/main.scss" | resources.ExecuteAsTemplate "style.main.scss" . | toCSS | minify | fingerprint }}
     <link rel="stylesheet" href="{{ $style.RelPermalink }}" integrity="{{ $style.Data.Integrity }}" crossorigin="anonymous" media="screen" />
 </head>