media: update KEY_CAPTURE_RATE javadoc

     * When capture rate is different than the frame rate, it means that the

     * video is acquired at a different rate than the playback, which produces

     * slow motion or timelapse effect during playback. Application can use the

     * value of this key to tell the relative speed ratio between capture and

     * playback rates when the video was recorded.

     * value of this key to set a capture rate that differs from the playback

     * rate. If unspecified, the system uses the playback frame rate as the

     * capture rate (e.g. normal speed).

     * </p>

     *

     * <p>However, Specifying capture rates that are nearly equal to the frame

     * rate are at risk of causing frame drops and other visual artifacts in

     * the output. To avoid such artifacts, the capture rate should be at

     * least a factor of 2 away from the frame rate.

     * {@code  GraphicBufferSource#calculateCodecTimestamp_l}</p>

     *

     * <p>

     * The associated value is an integer or a float.

     * </p>