Document BlockStack and make linter happ[y/ier].

ansi/paragraph.go

@@ -8,7 +8,7 @@ import (
 	"github.com/muesli/reflow/wordwrap"
 )
 
-// ParagraphElements are used to render individual paragraphs.
+// A ParagraphElement is used to render individual paragraphs.
 type ParagraphElement struct {
 	First bool
 }