Move kafka dashboard changelog entry to correct place (#8672)

(cherry picked from commit 9999fe9)

CHANGELOG.asciidoc

@@ -79,7 +79,6 @@ https://github.com/elastic/beats/compare/v6.4.0...6.x[Check the HEAD diff]
 - Recover metrics for old apache versions removed by mistake on #6450. {pull}7871[7871]
 - Fix dropwizard module parsing of metric names. {issue}8365[8365] {pull}6385[8385]
 - Fix issue that would prevent kafka module to find a proper broker when port is not set {pull}8613[8613]
-- Add Kafka dashboard. {pull}8457[8457]
 
 *Packetbeat*
 
@@ -140,6 +139,7 @@ https://github.com/elastic/beats/compare/v6.4.0...6.x[Check the HEAD diff]
 - Add container image for docker metricsets. {issue}8214[8214] {pull}8438[8438]
 - Precalculate composed id fields for kafka dashboards. {pull}8504[8504]
 - Add support for `full` status page output for php-fpm module as a separate metricset called `process`. {pull}8394[8394]
+- Add Kafka dashboard. {pull}8457[8457]
 
 *Packetbeat*