For R6 deliver, both RTD and WIKI updates for DL-handler are required by M4

WIKI (https://wiki.onap.org/display/DW/DCAE+R6+DL-Handler+MicroService) should be updated for R6 to include deployment/validation steps - this will be used for demo after M4.

The official releases notes are maintained under dcaegen2 repo (https://git.onap.org/dcaegen2/tree/docs/sections/services). New sub-folder to be created for DL-handler and information similar to other MS to be added as rst (Overview, architecture/flow, installation, troubleshooting, configuration management etc)