[KARAF-3225] Release Apache Karaf 2.3.8. Update online release notes

git-svn-id: https://svn.apache.org/repos/asf/karaf/site/trunk@1625198 13f79535-47bb-0310-9956-ffa450edef68
[KARAF-3225] Release Apache Karaf 2.3.8. Update deps table

git-svn-id: https://svn.apache.org/repos/asf/karaf/site/trunk@1625201 13f79535-47bb-0310-9956-ffa450edef68