- Fixed doxygen syntax to standard '\' instead of '@'

diff --git a/library/x509parse.c b/library/x509parse.c
index 7a5fdad..378f0a9 100644
--- a/library/x509parse.c
+++ b/library/x509parse.c
@@ -2631,7 +2631,7 @@
 /*
  * Wrapper for x509 hashes.
  *
- * @param out   Buffer to receive the hash (Should be at least 64 bytes)
+ * \param out   Buffer to receive the hash (Should be at least 64 bytes)
  */
 static void x509_hash( const unsigned char *in, int len, int alg,
                        unsigned char *out )