SubGhz: refactoring add descriptions (#1012)

* SubGhz: add descriptions
* SubGhz: fix syntax

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

lib/subghz/protocols/registry.h

@@ -2,8 +2,22 @@
 
 #include "../types.h"
 
+/**
+ * Registration by name SubGhzProtocol.
+ * @param name Protocol name
+ * @return SubGhzProtocol* pointer to a SubGhzProtocol instance
+ */
 const SubGhzProtocol* subghz_protocol_registry_get_by_name(const char* name);
 
+/**
+ * Registration protocol by index in array SubGhzProtocol.
+ * @param index Protocol by index in array
+ * @return SubGhzProtocol* pointer to a SubGhzProtocol instance
+ */
 const SubGhzProtocol* subghz_protocol_registry_get_by_index(size_t index);
 
+/**
+ * Getting the number of registered protocols.
+ * @return Number of protocols
+ */
 size_t subghz_protocol_registry_count();