Fix Prometheus metrics doc (#6514)

Additionally, make validate-metrics-doc.sh output the diff if there is.

Signed-off-by: Quan Tian <quan.tian@broadcom.com>

ci/kind/validate-metrics-doc.sh

@@ -37,7 +37,7 @@ METRICS_DOC="$THIS_DIR/../../docs/prometheus-integration.md"
 cp -v $METRICS_DOC $METRICS_TMP_DOC
 $MAKE_CMD $METRICS_TMP_DOC
 result=0
-cmp -s $METRICS_DOC $METRICS_TMP_DOC || result=$?
+diff $METRICS_DOC $METRICS_TMP_DOC || result=$?
 if [ $result -ne 0 ]; then
     echo "Error: Prometheus metrics document should be updated"
     echo "You can update it by building the Antrea Docker image locally (with 'make'), running ./hack/make-metrics-doc.sh and committing the changes"

docs/prometheus-integration.md

@@ -477,6 +477,9 @@ to a non-default GODEBUG=multipartmaxparts=... setting.
 - **go_godebug_non_default_behavior_multipathtcp_events_total:** The number
 of non-default behaviors executed by the net package due to a non-default
 GODEBUG=multipathtcp=... setting.
+- **go_godebug_non_default_behavior_netedns0_events_total:** The number
+of non-default behaviors executed by the net package due to a non-default
+GODEBUG=netedns0=... setting.
 - **go_godebug_non_default_behavior_panicnil_events_total:** The number of
 non-default behaviors executed by the runtime package due to a non-default
 GODEBUG=panicnil=... setting.