doxygen: enable AUTOBRIEF, drop \brief

Especially for short descriptions, it is annoying to have to type \brief for
every single API doc.

Drop all \brief and enable the AUTOBRIEF feature of doxygen, which always takes
the first sentence of an API doc as the brief description.

Change-Id: I11a8a821b065a128108641a2a63fb5a2b1916e87
diff --git a/src/vty/utils.c b/src/vty/utils.c
index 6772593..267d76e 100644
--- a/src/vty/utils.c
+++ b/src/vty/utils.c
@@ -67,7 +67,7 @@
 	return 0;
 }
 
-/*! \brief print a rate counter group to given VTY
+/*! print a rate counter group to given VTY
  *  \param[in] vty The VTY to which it should be printed
  *  \param[in] prefix Any additional log prefix ahead of each line
  *  \param[in] ctrg Rate counter group to be printed
@@ -126,7 +126,7 @@
 	return 0;
 }
 
-/*! \brief print a stat item group to given VTY
+/*! print a stat item group to given VTY
  *  \param[in] vty The VTY to which it should be printed
  *  \param[in] prefix Any additional log prefix ahead of each line
  *  \param[in] statg Stat item group to be printed
@@ -200,7 +200,7 @@
 	vty_out_statistics_partial(vty, prefix, INT_MAX);
 }
 
-/*! \brief Generate a VTY command string from value_string */
+/*! Generate a VTY command string from value_string */
 char *vty_cmd_string_from_valstr(void *ctx, const struct value_string *vals,
 				 const char *prefix, const char *sep,
 				 const char *end, int do_lower)