BTS-719 | Query explain output for 3.9 traversal optimizations (#877)
BTS-719 | Query explain output for 3.9 traversal optimizations (#877)

* Query explain output for traversal optimizations

* Update release-notes-new-features39.md

Co-authored-by: ansoboleva <88632894a9e531c470067a10e46d4700ecadd961@users.noreply.github.com>
arangodb/docs,arangodb/docs,arangodb/docs,arangodb/docs