Use proper doxygen markup to mark deprecations
diff --git a/include/polarssl/pbkdf2.h b/include/polarssl/pbkdf2.h
index 5c06bfb..e842c83 100644
--- a/include/polarssl/pbkdf2.h
+++ b/include/polarssl/pbkdf2.h
@@ -2,7 +2,8 @@
  * \file pbkdf2.h
  *
  * \brief Password-Based Key Derivation Function 2 (from PKCS#5)
- *        DEPRECATED: use pkcs5.h instead.
+ *
+ * \deprecated Use pkcs5.h instead.
  *
  * \author Mathias Olsson <mathias@kompetensum.com>
  *
@@ -46,7 +47,8 @@
 
 /**
  * \brief          PKCS#5 PBKDF2 using HMAC
- *                 DEPRECATED: Use pkcs5_pbkdf2_hmac() instead!
+ *
+ * \deprecated     Use pkcs5_pbkdf2_hmac() instead
  *
  * \param ctx      Generic HMAC context
  * \param password Password to use when generating key
@@ -66,7 +68,8 @@
 
 /**
  * \brief          Checkup routine
- *                 DEPRECATED: Use pkcs5_self_test() instead!
+ *
+ * \deprecated     Use pkcs5_self_test() instead
  *
  * \return         0 if successful, or 1 if the test failed
  */