Adds Alvin Chen's new introduction section to replace old Logstash reference's preface

Fixes #3803

docs/asciidoc/static/introduction.asciidoc

@@ -0,0 +1,110 @@
+[[logstash-power]]
+=== The Power of Logstash
+
+[horizontal]
+*The ingestion workhorse for Elasticsearch and more*:: Horizontally scalable data processing pipeline with strong 
+Elasticsearch and Kibana synergy
+*Pluggable pipeline architecture*:: Mix, match, and orchestrate different inputs, filters, and outputs to play in 
+pipeline harmony
+*Community-extensible and developer-friendly plugin ecosystem*:: Over 200 plugins available, plus the flexibility of 
+creating and contributing your own
+
+image:images/logstash.png[]
+
+[float]
+=== Logstash Loves Data
+
+Collect more, so you can know more. Logstash welcomes data of all shapes and sizes.
+
+==== Logs and Metrics
+
+Where it all started.
+
+* Handle all types of logging data
+** Easily ingest a multitude of web logs like {logstash}advanced-pipeline.html#parsing-into-es[Apache], and application 
+logs like {logstash}plugins-inputs-log4j.html[log4j] for Java
+** Capture many other log formats like {logstash}plugins-inputs-syslog.html[syslog], 
+{logstash}plugins-inputs-eventlog.html[Windows event logs], networking and firewall logs, and more
+* Enjoy complementary secure log forwarding capabilities with 
+https://github.com/elastic/logstash-forwarder[Logstash Forwarder]
+* Collect metrics from {logstash}plugins-inputs-ganglia.html[Ganglia], {logstash}plugins-codecs-collectd.html[collectd], 
+{logstash}plugins-codecs-netflow.html[NetFlow], {logstash}plugins-inputs-jmx.html[JMX], and many other infrastructure 
+and application platforms over {logstash}plugins-inputs-tcp.html[TCP] and {logstash}plugins-inputs-udp.html[UDP]
+
+==== The Web
+
+Unlock the World Wide Web.
+
+* Transform {logstash}plugins-inputs-http.html[HTTP requests] into events 
+(https://www.elastic.co/blog/introducing-logstash-input-http-plugin[blog])
+** Consume from web service firehoses like {logstash}plugins-inputs-twitter.html[Twitter] for social sentiment analysis
+** Webhook support for GitHub, HipChat, JIRA, and countless other applications
+** Enables many https://www.elastic.co/guide/en/watcher/current/logstash-integration.html[Watcher] alerting use cases
+* Create events by polling {logstash}plugins-inputs-http_poller.html[HTTP endpoints] on demand 
+(https://www.elastic.co/blog/introducing-logstash-http-poller[blog])
+** Universally capture health, performance, metrics, and other types of data from web application interfaces
+** Perfect for scenarios where the control of polling is preferred over receiving
+
+==== Data Stores and Streams
+
+Discover more value from the data you already own.
+
+* Better understand your data from any relational database or NoSQL store with a {logstash}plugins-inputs-jdbc.html[JDBC] 
+interface (https://www.elastic.co/blog/logstash-jdbc-input-plugin[blog])
+* Unify diverse data streams from messaging queues like Apache {logstash}plugins-outputs-kafka.html[Kafka] 
+(https://www.elastic.co/blog/logstash-kafka-intro[blog]), {logstash}plugins-outputs-rabbitmq.html[RabbitMQ], 
+{logstash}plugins-outputs-sqs.html[Amazon SQS], and {logstash}plugins-outputs-zeromq.html[ZeroMQ]
+
+==== Sensors and IoT
+
+Explore an expansive breadth of other data.
+
+* In this age of technological advancement, the massive IoT world unleashes endless use cases through capturing and 
+harnessing data from connected sensors.
+* Logstash is the common event collection backbone for ingestion of data shipped from mobile devices to intelligent homes, 
+connected vehicles, healthcare sensors, and many other industry specific applications.
+* https://www.elastic.co/elasticon/2015/sf/if-it-moves-measure-it-logging-iot-with-elk[Watch] as Logstash, in 
+conjunction with the broader ELK stack, centralizes and enriches sensor data to gain deeper knowledge regarding a 
+residential home.
+
+[float]
+=== Easily Enrich Everything
+
+The better the data, the better the knowledge. Clean and transform your data during ingestion to gain near real-time 
+insights immediately at index or output time. Logstash comes out-of-box with many aggregations and mutations along with 
+pattern matching, geo mapping, and dynamic lookup capabilities.
+
+* {logstash}plugins-filters-grok.html[Grok] is the bread and butter of Logstash filters and is used ubiquitously to 
+derive structure out of unstructured data. Enjoy a wealth of integrated patterns aimed to help quickly resolve web, 
+systems, networking, and other types of event formats.
+* Expand your horizons by deciphering {logstash}plugins-filters-geoip.html[geo coordinates] from IP addresses, normalizing {logstash}plugins-filters-date.html[date] complexity, simplifying {logstash}plugins-filters-kv.html[key-value pairs] and {logstash}plugins-filters-csv.html[CSV] data, {logstash}plugins-filters-anonymize.html[anonymizing] sensitive information, and further enriching your data with {logstash}plugins-filters-translate.html[local lookups] or Elasticsearch {logstash}plugins-filters-elasticsearch.html[queries].
+* Codecs are often used to ease the processing of common event structures like {logstash}plugins-codecs-json.html[JSON] and {logstash}plugins-codecs-multiline.html[multiline] events.
+
+[float]
+=== Choose Your Stash
+
+Route your data where it matters most. Unlock various downstream analytical and operational use cases by storing, analyzing, and taking action on your data.
+
+|=======================================================================
+| *Analysis*          
+* {logstash}plugins-outputs-elasticsearch.html[Elasticsearch]
+* Data stores such as {logstash}plugins-outputs-mongodb.html[MongoDB] and {logstash}plugins-outputs-riak.html[Riak]
+| *Archiving*
+* {logstash}plugins-outputs-webhdfs.html[HDFS]
+* {logstash}plugins-outputs-s3.html[S3]
+* {logstash}plugins-outputs-google_cloud_storage.html[Google Cloud Storage]
+| *Monitoring*          
+* {logstash}plugins-outputs-nagios.html[Nagios]
+* {logstash}plugins-outputs-ganglia.html[Ganglia]
+* {logstash}plugins-outputs-zabbix.html[Zabbix]
+* {logstash}plugins-outputs-graphite.html[Graphite]
+* {logstash}plugins-outputs-datadog.html[Datadog]
+* {logstash}plugins-outputs-cloudwatch.html[CloudWatch]
+| *Alerting*
+* https://www.elastic.co/products/watcher[Watcher] with Elasticsearch
+* {logstash}plugins-outputs-email.html[Email]
+* {logstash}plugins-outputs-pagerduty.html[Pagerduty]
+* {logstash}plugins-outputs-hipchat.html[HipChat]
+* {logstash}plugins-outputs-irc.html[IRC]
+* {logstash}plugins-outputs-sns.html[SNS]
+|=======================================================================