Fixed doxygen blocks
(cherry picked from commit 77db6ce3481ad610ee786d5ab171d5d10c1cb59d)
diff --git a/include/polarssl/arc4.h b/include/polarssl/arc4.h
index 48ad60b..7233384 100644
--- a/include/polarssl/arc4.h
+++ b/include/polarssl/arc4.h
@@ -66,7 +66,7 @@
 int arc4_crypt( arc4_context *ctx, size_t length, const unsigned char *input,
                 unsigned char *output );
 
-/*
+/**
  * \brief          Checkup routine
  *
  * \return         0 if successful, or 1 if the test failed