Bump to scalafix 0.9.0-RC1

Author: MasseGuillaume

README.md

@@ -46,7 +46,7 @@ We created two migration rules:
 ```scala
 // project/plugins.sbt
 
-addSbtPlugin("ch.epfl.scala" % "sbt-scalafix" % "0.7.0-RC1")
+addSbtPlugin("ch.epfl.scala" % "sbt-scalafix" % "0.9.0-RC1")
 ```
 
 ```scala
@@ -62,11 +62,10 @@ libraryDependencies += collectionCompat // required for Collection213CrossCompat
 addCompilerPlugin(scalafixSemanticdb)
 scalacOptions ++= List(
   "-Yrangepos",
-  "-Ywarn-unused-import",
-  "-P:semanticdb:synthetics:on"
+  "-P:semanticdb:synthetics:on" // Required by the collection rewrites
 )
 
-scalafixDependencies in ThisBuild += "org.scala-lang.modules" %% "scala-collection-migrations" % Dependencies.collectionCompatVersion
+scalafixDependencies in ThisBuild += "org.scala-lang.modules" %% "scala-collection-migrations" % collectionCompatVersion
 ```
 
 Then run:
@@ -77,6 +76,8 @@ Then run:
 > ;scalafix Collection213CrossCompat ;test:scalafix Collection213CrossCompat # For Libraries
 ```
 
+The official documentation: https://scalacenter.github.io/scalafix/docs/users/installation.html
+
 The migration tool is not exhaustive and we will continue to improve
 it over time. If you encounter a use case that’s not supported, please
 report it as described in the

build.sbt

@@ -162,10 +162,6 @@ lazy val `scalafix-data` = MultiScalaProject(
   "scalafix/data",
   _.settings(sharedScalafixSettings)
     .settings(dontPublish)
-    .settings(
-      addCompilerPlugin(scalafixSemanticdb),
-      scalacOptions += "-P:semanticdb:synthetics:on"
-    )
 )
 
 val `scalafix-data211` = `scalafix-data`(scala211, _.dependsOn(compat211JVM))