Update java-interop.md
Kramdown extension plugin added
Styles for heading anchors
Merge branch 'master' into headline-anchors
Merge branch 'master' into dev

Conflicts:
	docs/reference/java-interop.md
Api docs support
Merge branch 'master' into headline-anchors
Cosmetics
Merge branch 'headline-anchors' into dev
Merge branch 'master' into dev
#KT-5729 Headline anchors improvements
Merge branch 'headline-anchors' into dev
Added dev and prod environment support in rake
Merge branch 'env-support' into api-docs
Merge branch 'master' into dev
Merge branch 'api-docs' into dev
Merge branch 'headline-anchors' into dev
Merge remote-tracking branch 'origin/dev' into dev