improve docs

include/tgbot.h

@@ -6,15 +6,19 @@
 #include "types.h"
 
 /**
- * Initializes the Bot object
- * @param[out] bot The Bot object
- * @param[in] token The Bot token (obtained from @BotFather)
+ * @brief Initializes the Bot object.
+ *
+ * @param[out] bot The Bot object.
+ * @param[in] token The Bot token (obtained from @BotFather).
+ *
+ * @return TGBOT_OK on success.
  */
 tgbot_rc tgbot_init(tgbot *bot, char *token);
 
 /**
- * Cleans the memory
- * @param bot The Bot object
+ * @brief Cleans the memory.
+ *
+ * @param[out] bot The Bot object.
  */
 void tgbot_destroy(tgbot *bot);