Docker: added new chapter to introduce docker images for syslog-ng

SUMMARY.md

@@ -29,4 +29,5 @@
     * [Simple Python Destination](chapters/chapter_5/section_1.md)
     * [Simple Java Destination](chapters/chapter_5/section_2.md)
     * [Python Kafka Destination](chapters/chapter_5/section_3.md)
-    * [Osquery and Elasticsearch](chapters/chapter_5/section_4.md)
+    * [Osquery and Elasticsearch](chapters/chapter_5/section_4.md)
+* [docker images for syslog-ng](chapters/chapter_6/README.md)

chapters/chapter_6/README.md

@@ -0,0 +1,20 @@
+## docker images for syslog-ng
+
+### Available docker images
+* **balabit/syslog-ng**:
+    * Within this docker image syslog-ng and syslog-ng incubator is installed from deb package.
+    * It is intended to be used as a system logging service.
+* **balabit/syslog-ng-dev**:
+    * This is a development image for building and testing syslog-ng.
+    * It contains all packages to build and debug syslog-ng within the container.
+* **balabit/syslog-ng-incubator-dev**:
+    * This is a development image for building and testing syslog-ng incubator.
+    * It contains all packages to build and debug syslog-ng-incubator within the container.
+
+### Availability and description of docker images
+
+#### Place of docker images
+* https://hub.docker.com/r/balabit/
+
+#### Source project of docker images
+* https://github.com/balabit/syslog-ng-docker