SubGhz: refactoring add descriptions (#1012)

* SubGhz: add descriptions
* SubGhz: fix syntax

Co-authored-by: あく <alleteam@gmail.com>

lib/subghz/transmitter.h

@@ -11,13 +11,37 @@ struct SubGhzTransmitter {
     SubGhzProtocolEncoderBase* protocol_instance;
 };
 
+/**
+ * Allocate and init SubGhzTransmitter.
+ * @param environment Pointer to a SubGhzEnvironment instance
+ * @return SubGhzTransmitter* pointer to a SubGhzTransmitter instance
+ */
 SubGhzTransmitter*
     subghz_transmitter_alloc_init(SubGhzEnvironment* environment, const char* protocol_name);
 
+/**
+ * Free SubGhzTransmitter.
+ * @param instance Pointer to a SubGhzTransmitter instance
+ */
 void subghz_transmitter_free(SubGhzTransmitter* instance);
 
+/**
+ * Forced transmission stop.
+ * @param instance Pointer to a SubGhzTransmitter instance
+ */
 bool subghz_transmitter_stop(SubGhzTransmitter* instance);
 
+/**
+ * Deserialize and generating an upload to send.
+ * @param instance Pointer to a SubGhzTransmitter instance
+ * @param flipper_format Pointer to a FlipperFormat instance
+ * @return true On success
+ */
 bool subghz_transmitter_deserialize(SubGhzTransmitter* instance, FlipperFormat* flipper_format);
 
+/**
+ * Getting the level and duration of the upload to be loaded into DMA.
+ * @param context Pointer to a SubGhzTransmitter instance
+ * @return LevelDuration 
+ */
 LevelDuration subghz_transmitter_yield(void* context);