[doc] Properly define 'oap' group and add introductory text
Change-Id: I1e875991ae1dd93862f850f85d40b3dac61ece72
diff --git a/include/osmocom/gsm/oap.h b/include/osmocom/gsm/oap.h
index ef83b79..ce1e151 100644
--- a/include/osmocom/gsm/oap.h
+++ b/include/osmocom/gsm/oap.h
@@ -1,5 +1,12 @@
-/*! \file oap.h
- * Osmocom Authentication Protocol message encoder/decoder. */
+/*! \defgroup oap Osmocom Authentication Protocol
+ * @{
+ *
+ * The Osmocom Authentication Protocol (OAP) is a way to use the 3GPP
+ * AKA (Authentication and Key Agreement) as cryptographic
+ * authentication mechanism in other protocols that don't provide
+ * cryptographic authentication.
+ *
+ * \file oap.h */
/*
* (C) 2015-2016 by sysmocom s.f.m.c. GmbH
* All Rights Reserved
@@ -71,3 +78,5 @@
int osmo_oap_decode(struct osmo_oap_message *oap_msg, const uint8_t *data,
size_t data_len);
void osmo_oap_encode(struct msgb *msg, const struct osmo_oap_message *oap_msg);
+
+/*! @} */