Keep scss examples for v8, until first v9 release is out

Author: mkszepp

docs/app/components/snippets/installation-1.scss

@@ -1 +1,5 @@
+// ember-basic-dropdown v8.x
+@import "ember-basic-dropdown";
+
+// ember-basic-dropdown v9.x+
 @use "ember-basic-dropdown";

docs/app/components/snippets/styles-2.scss

@@ -1,3 +1,11 @@
+// ember-basic-dropdown v8.x
+// Define your variables first
+$ember-basic-dropdown-overlay-background: rgba(#3b5998, 0.5);
+
+// Then import the styles, which will use your variable
+@import "ember-basic-dropdown";
+
+// ember-basic-dropdown v9.x+
 // Define your variables first
 @use "ember-basic-dropdown/scss/variables.scss" with (
   $ember-basic-dropdown-overlay-background: rgba(#3b5998, 0.5)