Add MAX_FRAME_SIZE to adv config

docs/advanced_config.md

@@ -13,4 +13,5 @@ RF24Network offers many features, some of which can be configured by editing the
 | `#define DISABLE_USER_PAYLOADS` | This option will disable user-caching of payloads entirely. Use with RF24Ethernet to reduce memory usage. (TCP/IP is an external data type, and not cached)                                                            |
 | `#define ENABLE_SLEEP_MODE`     | Uncomment this option to enable sleep mode for AVR devices. (ATTiny,Uno, etc)                                                                                                                                          |
 | `#define ENABLE_NETWORK_STATS`  | Enable counting of all successful or failed transmissions, routed or sent directly                                                                                                                                     |
-| `#define NUM_PIPES`             | Define the number of pipes for addressing. The max value is generally hardware dependant. NRF24 supports 6 pipes, NRF52x supports 8 pipes                                                                                                                                     |
+| `#define NUM_PIPES`             | Define the number of pipes for addressing. The max value is generally hardware dependant. NRF24 supports 6 pipes, NRF52x supports 8 pipes                                                                              |
+| `#define MAX_FRAME_SIZE`        | Found in RF24Network.h, this allows users to set the maximum frame size used internally. NRF24 supports 32-bytes, NRF52x supports 123-bytes, or 111 if encryption is enabled                                           |