Fix setup guide in readme (#1444)

Add missing repository to load statement

Author: simuons

README.md

@@ -61,7 +61,7 @@ http_archive(
 load("@io_bazel_rules_scala//:scala_config.bzl", "scala_config")
 scala_config()
 
-load("//scala:scala.bzl", "rules_scala_setup", "rules_scala_toolchain_deps_repositories")
+load("@io_bazel_rules_scala//scala:scala.bzl", "rules_scala_setup", "rules_scala_toolchain_deps_repositories")
 
 # loads other rules Rules Scala depends on 
 rules_scala_setup()