fix: change to lowercase (#13)

close: #12, #9

Author: hichxm

adminlte-stubs/bootstrap/app.scss

@@ -2,4 +2,4 @@
 @import 'variables';
 
 // Bootstrap
-@import '~admin-lte/build/scss/AdminLTE';
+@import '~admin-lte/build/scss/adminlte';