use %button-primary placeholder

Author: denniserdmann

scss/components/_comments.scss

@@ -42,7 +42,7 @@ html {
 
   .submit {
     @extend %button;
-    @extend %btn--primary;
+    @extend %button--primary;
   }
 }
 

scss/components/_forms.scss

@@ -75,7 +75,7 @@ textarea.textarea {
 input.submit,
 button.submit {
   @extend %button;
-  @extend %btn--primary;
+  @extend %button--primary;
 }
 
 input[type="search"] {