Add doxygen documentation to libosmocoding

This adds the minimum amount of API documentation that we should have on
all our code, particularly new code merged into a library.

Change-Id: I526804f64313867913574e50e5b9e9205ad3aa74
diff --git a/include/osmocom/coding/gsm0503_parity.h b/include/osmocom/coding/gsm0503_parity.h
index 540124a..f844720 100644
--- a/include/osmocom/coding/gsm0503_parity.h
+++ b/include/osmocom/coding/gsm0503_parity.h
@@ -2,6 +2,14 @@
 
 #include <osmocom/core/crcgen.h>
 
+/*! \addtogroup parity
+ *  @{
+ */
+
+/*! \file gsm0503_parity.h
+ *  \brief GSM TS 05.03 parity
+ */
+
 const struct osmo_crc64gen_code gsm0503_fire_crc40;
 const struct osmo_crc16gen_code gsm0503_cs234_crc16;
 const struct osmo_crc8gen_code gsm0503_mcs_crc8_hdr;
@@ -11,3 +19,5 @@
 const struct osmo_crc8gen_code gsm0503_tch_fr_crc3;
 const struct osmo_crc8gen_code gsm0503_tch_efr_crc8;
 const struct osmo_crc8gen_code gsm0503_amr_crc6;
+
+/*! @} */