Issue 6864: Disable Mkdocs gradle plugin by default (#6865)
Issue 6864: Disable Mkdocs gradle plugin by default (#6865)

Sets gradle property enableMkdocs to false.

Signed-off-by: Derek Moore <e68edaac8327cb62075629f62d9bc4abc8599304@dell.com>

pravega/pravega,pravega/pravega,pravega/pravega