Add message to readme.md that the project is no longer maintained

[pcornelissen]

Spring social has been moved to the attic, to discourage poeple from using a dead project, it would be good to make a visible note in the readme.

[oi-io]

Or just do a 2.0 release

[pcornelissen]

I don't think that they will do a release for a dead project

[markhobson]

Is there any replacement for Spring Social if it's been disbanded?

[markhobson]

Looks like Spring Security 5 will gain Spring Social's OAuth client functionality. This EOL blog post should be linked to from the README:

https://spring.io/blog/2018/07/03/spring-social-end-of-life-announcement

Might save a few people going down a development dead end.