Reorder examples in README

Public issue https://github.com/mackron/miniaudio/issues/218

fix wrong assert in ma_open_stream__aaudio

Public issue https://github.com/mackron/miniaudio/issues/379

Public issue https://github.com/mackron/miniaudio/issues/379

This happens when the pEngine parameter is NULL.

  - ma_device_set_master_gain_db() > ma_device_set_master_volume_db()
  - ma_device_get_master_gain_db() > ma_device_get_master_volume_db()

This commit also relaxes the upper limit for volume control to allow
for amplification.

Public issue https://github.com/mackron/miniaudio/issues/377

This still needs some expansion.

  - ma_factor_to_gain_db > ma_volume_linear_to_db
  - ma_gain_db_to_factor > ma_volume_db_to_linear