Emit the end line in the JSON.

This handles the case where the end line is not on the same line as the
start line when using the new end column feature.

ShellCheck/Formatter/JSON.hs

@@ -40,6 +40,7 @@ instance JSON (PositionedComment) where
   showJSON comment@(PositionedComment start end (Comment level code string)) = makeObj [
       ("file", showJSON $ posFile start),
       ("line", showJSON $ posLine start),
+      ("endLine", showJSON $ posLine end),
       ("column", showJSON $ posColumn start),
       ("endColumn", showJSON $ posColumn end),
       ("level", showJSON $ severityText comment),