Mark decode_cef as GA in documentation (#17944)

decode_syslog is no longer in beta. It is used by the cef module which is not beta.

Co-authored-by: Andrew Kroh <andrew.kroh@elastic.co>
(cherry picked from commit 2e4c7c3)

CHANGELOG.next.asciidoc

@@ -250,6 +250,7 @@ https://github.com/elastic/beats/compare/v7.0.0-alpha2...master[Check the HEAD d
 - Improve AWS cloudtrail field mappings {issue}16086[16086] {issue}16110[16110] {pull}17155[17155]
 - Release Google Cloud module as GA. {pull}17511[17511]
 - Update filebeat httpjson input to support pagination via Header and Okta module. {pull}16354[16354]
+- Make `decode_cef` processor GA. {pull}17944[17944]
 
 *Heartbeat*
 

x-pack/filebeat/processors/decode_cef/decode_cef.go

@@ -14,7 +14,6 @@ import (
 
 	"github.com/elastic/beats/v7/libbeat/beat"
 	"github.com/elastic/beats/v7/libbeat/common"
-	"github.com/elastic/beats/v7/libbeat/common/cfgwarn"
 	"github.com/elastic/beats/v7/libbeat/logp"
 	"github.com/elastic/beats/v7/libbeat/processors"
 	"github.com/elastic/beats/v7/x-pack/filebeat/processors/decode_cef/cef"
@@ -45,8 +44,6 @@ func New(cfg *common.Config) (processors.Processor, error) {
 }
 
 func newDecodeCEF(c config) (*processor, error) {
-	cfgwarn.Beta("The " + procName + " processor is a beta feature.")
-
 	log := logp.NewLogger(logName)
 	if c.ID != "" {
 		log = log.With("instance_id", c.ID)

x-pack/filebeat/processors/decode_cef/docs/decode_cef.asciidoc

@@ -6,8 +6,6 @@
 <titleabbrev>decode_cef</titleabbrev>
 ++++
 
-beta[]
-
 The `decode_cef` processor decodes Common Event Format (CEF) messages. This
 processor is available in Filebeat.