message: Better documentation for `FIFOStream`.
diff: @@ -55,7 +55,7 @@ class FIFOInputStream : public BufferedInputStream, public WriteCallback {
  }
  /**
  - * Same as `reset(nullptr, nullptr, 0);.`
  + * Discards all data in the buffer and resets it to an empty state
  */
  void reset();
  @@ -126,6 +126,9 @@ class FIFOInputStream : public BufferedInputStream, public WriteCallback {
  */
  v_io_size commitReadOffset(v_buff_size count) override;
  + /**
  + * Reserve bytes for future writes. Check &id:oatpp::data::stream::FIFOStream::availableToWrite for the capacity.
  + */
  void reserveBytesUpfront(v_buff_size count);
  /**
  