Backport: Cherrypick community beats updates into 6.0 (#5115)

* Add etcdbeat to the community beats (#4915)

* Edit githubbeat description

libbeat/docs/communitybeats.asciidoc

@@ -33,12 +33,13 @@ https://github.com/Pravoru/consulbeat[consulbeat]:: Reads services health checks
 https://github.com/Ingensi/dockbeat[dockbeat]:: Reads Docker container
 statistics and indexes them in Elasticsearch.
 https://github.com/radoondas/elasticbeat[elasticbeat]:: Reads status from an Elasticsearch cluster and indexes them in Elasticsearch.
+https://github.com/gamegos/etcdbeat[etcdbeat]:: Reads stats from the Etcd v2 API and indexes them into Elasticsearch.
 https://github.com/christiangalsterer/execbeat[execbeat]:: Periodically executes shell commands and sends the standard output and standard error to
 Logstash or Elasticsearch.
 https://github.com/jarpy/factbeat[factbeat]:: Collects facts from https://puppetlabs.com/facter[Facter].
 https://github.com/FStelzer/flowbeat[flowbeat]:: Collects, parses, and indexes http://www.sflow.org/index.php[sflow] samples.
 https://github.com/GeneralElectric/GABeat[gabeat]:: Collects data from Google Analytics Realtime API.
-https://github.com/jlevesy/githubbeat[githubbeat]:: Easily monitor github repositories activity
+https://github.com/jlevesy/githubbeat[githubbeat]:: Easily monitors GitHub repository activity.
 https://github.com/hpcugent/gpfsbeat[gpfsbeat]:: Collects GPFS metric and quota information.
 https://github.com/YaSuenag/hsbeat[hsbeat]:: Reads all performance counters in Java HotSpot VM.
 https://github.com/christiangalsterer/httpbeat[httpbeat]:: Polls multiple HTTP(S) endpoints and sends the data to