docs: Document EBUSY on stream API functions

Signed-off-by: Rahix <rahix@rahix.de>

epicardium/epicardium.h

@@ -92,6 +92,7 @@ API(API_LEDS_SET, void epic_leds_set(int led, uint8_t r, uint8_t g, uint8_t b));
  *    - ``-ENODEV``: Sensor is not currently available.
  *    - ``-EBADF``: The given sensor descriptor is unknown.
  *    - ``-EINVAL``:  ``count`` is not a multiple of the sensor's sample size.
+ *    - ``-EBUSY``: The descriptor table lock could not be acquired.
  *
  * **Example**:
  *

epicardium/modules/stream.h

@@ -60,6 +60,7 @@ struct stream_info {
  *
  *    - ``-EINVAL``: Out of range sensor descriptor.
  *    - ``-EACCES``: Stream already registered.
+ *    - ``-EBUSY``: The descriptor lock could not be acquired.
  */
 int stream_register(int sd, struct stream_info *stream);
 
@@ -74,6 +75,7 @@ int stream_register(int sd, struct stream_info *stream);
  *
  *    - ``-EINVAL``: Out of range sensor descriptor.
  *    - ``-EACCES``: Stream ``stream`` was not registered for ``sd``.
+ *    - ``-EBUSY``: The descriptor lock could not be acquired.
  */
 int stream_deregister(int sd, struct stream_info *stream);