Fix wrong \file name in Doxygen comments

Signed-off-by: Gilles Peskine <Gilles.Peskine@arm.com>
diff --git a/library/md.c b/library/md.c
index de77b16..a10a835 100644
--- a/library/md.c
+++ b/library/md.c
@@ -1,5 +1,5 @@
 /**
- * \file mbedtls_md.c
+ * \file md.c
  *
  * \brief Generic message digest wrapper for mbed TLS
  *