Update writing_queries.md to fix grammar

Sounded weird.

docs/content/en/docs/Getting started/writing_queries.md

@@ -119,7 +119,7 @@ Future update(Todo entry) {
   // using replace will update all fields from the entry that are not marked as a primary key.
   // it will also make sure that only the entry with the same primary key will be updated.
   // Here, this means that the row that has the same id as entry will be updated to reflect
-  // the entry's title, content and category. As it set's its where clause automatically, it
+  // the entry's title, content and category. As its where clause is set automatically, it
   // cannot be used together with where.
   return update(todos).replace(entry);
 }