message: fix docs for approximateSize() callback
diff: @@ -170,7 +170,7 @@ The `callback` function will be called with no arguments if the operation is suc
  The `start` and `end` parameters may be strings or Buffers representing keys in the LevelDB store.
  -The `callback` function will be called with no arguments if the operation is successful or with a single `error` argument if the operation failed for any reason.
  +The `callback` function will be called with a single `error` if the operation failed for any reason. If successful the first argument will be `null` and the second argument will be the approximate size as a Number.
  <a name="leveldown_compactRange"></a>
  ### `db.compactRange(start, end, callback)`
  