Artima Supersafe plugin installation instructions incorrect

[readytopark]

addSbtPlugin("com.artima.supersafe" % "sbtplugin" % "1.1.3") causes errors like this.

...
[info] Updating ...
[warn] 	module not found: com.artima.supersafe#supersafe_2.12.6;1.1.3
[warn] ==== local: tried
[warn]   /Users/jonghoonpark/.ivy2/local/com.artima.supersafe/supersafe_2.12.6/1.1.3/ivys/ivy.xml
[warn] ==== public: tried
[warn]   https://repo1.maven.org/maven2/com/artima/supersafe/supersafe_2.12.6/1.1.3/supersafe_2.12.6-1.1.3.pom
[warn] ==== local-preloaded-ivy: tried
[warn]   /Users/jonghoonpark/.sbt/preloaded/com.artima.supersafe/supersafe_2.12.6/1.1.3/ivys/ivy.xml
[warn] ==== local-preloaded: tried
[warn]   file:////Users/jonghoonpark/.sbt/preloaded/com/artima/supersafe/supersafe_2.12.6/1.1.3/supersafe_2.12.6-1.1.3.pom
[warn] ==== Artima Maven Repository: tried
[warn]   http://repo.artima.com/releases/com/artima/supersafe/supersafe_2.12.6/1.1.3/supersafe_2.12.6-1.1.3.pom
...

When I visited the url(http://repo.artima.com/releases/com/artima/supersafe/supersafe_2.12.6/) to check what's available, it appears that only 1.1.5 or 1.1.6 are supported. After changing version to either of them seems to work.