summary: add SkyWalking docs (#747)

Signed-off-by: lecaros <[email protected]>

Author: lecaros

SUMMARY.md

@@ -134,23 +134,20 @@
   * [Throttle](pipeline/filters/throttle.md)
   * [Tensorflow](pipeline/filters/tensorflow.md)
 * [Outputs](pipeline/outputs/README.md)
-  * [OpenTelemetry](pipeline/outputs/opentelemetry.md)
-  * [Prometheus Exporter](pipeline/outputs/prometheus-exporter.md)
-  * [Prometheus Remote Write](pipeline/outputs/prometheus-remote-write.md)
   * [Amazon CloudWatch](pipeline/outputs/cloudwatch.md)
   * [Amazon Kinesis Data Firehose](pipeline/outputs/firehose.md)
   * [Amazon Kinesis Data Streams](pipeline/outputs/kinesis.md)
   * [Amazon S3](pipeline/outputs/s3.md)
-  * [Azure Log Analytics](pipeline/outputs/azure.md)
   * [Azure Blob](pipeline/outputs/azure_blob.md)
-  * [Google Cloud BigQuery](pipeline/outputs/bigquery.md)
+  * [Azure Log Analytics](pipeline/outputs/azure.md)
   * [Counter](pipeline/outputs/counter.md)
   * [Datadog](pipeline/outputs/datadog.md)
   * [Elasticsearch](pipeline/outputs/elasticsearch.md)
   * [File](pipeline/outputs/file.md)
   * [FlowCounter](pipeline/outputs/flowcounter.md)
   * [Forward](pipeline/outputs/forward.md)
   * [GELF](pipeline/outputs/gelf.md)
+  * [Google Cloud BigQuery](pipeline/outputs/bigquery.md)
   * [HTTP](pipeline/outputs/http.md)
   * [InfluxDB](pipeline/outputs/influxdb.md)
   * [Kafka](pipeline/outputs/kafka.md)
@@ -160,11 +157,15 @@
   * [NATS](pipeline/outputs/nats.md)
   * [New Relic](pipeline/outputs/new-relic.md)
   * [NULL](pipeline/outputs/null.md)
+  * [OpenTelemetry](pipeline/outputs/opentelemetry.md)
   * [PostgreSQL](pipeline/outputs/postgresql.md)
+  * [Prometheus Exporter](pipeline/outputs/prometheus-exporter.md)
+  * [Prometheus Remote Write](pipeline/outputs/prometheus-remote-write.md)
+  * [SkyWalking](pipeline/outputs/skywalking.md)
   * [Slack](pipeline/outputs/slack.md)
+  * [Splunk](pipeline/outputs/splunk.md)
   * [Stackdriver](pipeline/outputs/stackdriver.md)
   * [Standard Output](pipeline/outputs/standard-output.md)
-  * [Splunk](pipeline/outputs/splunk.md)
   * [Syslog](pipeline/outputs/syslog.md)
   * [TCP & TLS](pipeline/outputs/tcp-and-tls.md)
   * [Treasure Data](pipeline/outputs/treasure-data.md)