extend telegramheader doc with adding nore for DATA_CHECKSUM and COMPRESSOR_ID fields

Author: w0lek

vpr/src/server/telegramheader.h

@@ -19,6 +19,10 @@ namespace comm {
  * - [ 4 bytes ]: DATA_LENGTH - A 4-byte field where the data length is stored, allowing for proper identification of the start and end of the TelegramFrame sequence.
  * - [ 4 bytes ]: DATA_CHECKSUM - A 4-byte field where the data checksum is stored to validate the attached data.
  * - [ 1 byte ]: COMPRESSOR_ID - A 1-byte field where the compressor id is stored. If it's \0, it means the data is not compressed (in text/json format).
+ *
+ * @note: Currently, only zlib compression for the telegram body is supported, which is specified with COMPRESSOR_ID='z'.
+ *
+ * @note: The DATA_CHECKSUM field can be used to check the integrity of the telegram body on the client app side.
  */
 class TelegramHeader {
 public: