Correct the typo in the TODO of README.md
Merge pull request #13 from wyukawa/feature-typo

Correct the typo in the TODO of README.md
fix to check callback error correctly
 * HiveServer(and 2) does NOT return error for schema call
   * schema callback is meta-callback, one of result fetches
 * Presto client library returns error on first fetch of its status
   * this is equal of schema fetch