util/token: add docs

include/util/token.h

@@ -3,8 +3,14 @@
 
 #include <stdbool.h>
 
+/**
+ * Number of bytes used by a token, including the terminating zero byte.
+ */
 #define TOKEN_SIZE 33
 
+/**
+ * Generate a random token string.
+ */
 bool generate_token(char out[static TOKEN_SIZE]);
 
 #endif