what does google searchable mean?

It means the content here can be found on Google. Some time it can take some time before it gets index but if you look at communities like http://slack-chats.kotlinlang.org/http://slack-chats.kotlinlang.org/http://slack-chats.kotlinlang.org/ and google site:http://slack-chats.kotlinlang.org/ kotlin you'll see conversations showing up