Adds shared version file (#1882)

Author: lcawl

shared/versions/stack/7.9.asciidoc

@@ -0,0 +1,32 @@
+:version:                7.9.0
+////
+bare_version never includes -alpha or -beta
+////
+:bare_version:           7.9.0
+:logstash_version:       7.9.0
+:elasticsearch_version:  7.9.0
+:kibana_version:         7.9.0
+:apm_server_version:     7.9.0
+:branch:                 7.9
+:minor-version:          7.9
+:major-version:          7.x
+:prev-major-version:     6.x
+:major-version-only:     7
+:ecs_version:            1.4
+
+//////////
+release-state can be: released | prerelease | unreleased
+//////////
+
+:release-state:          unreleased
+
+////
+APM Agent versions
+////
+:apm-go-branch:         1.x
+:apm-java-branch:       1.x
+:apm-rum-branch:        5.x
+:apm-node-branch:       3.x
+:apm-py-branch:         5.x
+:apm-ruby-branch:       3.x
+:apm-dotnet-branch:     1.x