Documentation: xfrm_sync: Trim excess section heading characters

The first section "Message Structure" has excess underline, while the
second and third one ("TLVS reflect the different parameters" and
"Default configurations for the parameters") have trailing colon. Trim
them.

Reviewed-by: Randy Dunlap <rdunlap@infradead.org>
Tested-by: Randy Dunlap <rdunlap@infradead.org>
Suggested-by: Randy Dunlap <rdunlap@infradead.org>
Signed-off-by: Bagas Sanjaya <bagasdotme@gmail.com>
Signed-off-by: Steffen Klassert <steffen.klassert@secunet.com>

Documentation/networking/xfrm_sync.rst

@@ -36,7 +36,7 @@ is not driven by packet arrival.
 - the replay sequence for both inbound and outbound
 
 1) Message Structure
-----------------------
+--------------------
 
 nlmsghdr:aevent_id:optional-TLVs.
 
@@ -83,8 +83,8 @@ when going from kernel to user space)
 A program needs to subscribe to multicast group XFRMNLGRP_AEVENTS
 to get notified of these events.
 
-2) TLVS reflect the different parameters:
------------------------------------------
+2) TLVS reflect the different parameters
+----------------------------------------
 
 a) byte value (XFRMA_LTIME_VAL)
 
@@ -106,8 +106,8 @@ d) expiry timer (XFRMA_ETIMER_THRESH)
    This is a timer value in milliseconds which is used as the nagle
    value to rate limit the events.
 
-3) Default configurations for the parameters:
----------------------------------------------
+3) Default configurations for the parameters
+--------------------------------------------
 
 By default these events should be turned off unless there is
 at least one listener registered to listen to the multicast