Add sbt-vspp for publishing the SBT plug-in in a Maven-consistent format

This is to enable usage of sbt-scalafmt in Enterprise environments where only the valid-POM format is accepted for JAR downloads, enabling advanced Scala capabilities for many many environments. Currently the only way to use it is by manual republishing but we rather any updates get made available automatically.

The only change this does is to add extra JAR and POM to the released artifact (while keeping the old structure -- notice how when you click on 'Browse' on here https://search.maven.org/artifact/org.scalameta/sbt-scalafmt/2.4.6/jar - it goes to a 404 Not Found page.

More background here: https://github.com/esbeetee/sbt-vspp/blob/main/README.md

project/plugins.sbt

@@ -1,2 +1,3 @@
 addSbtPlugin("com.geirsson" % "sbt-ci-release" % "1.5.6")
 libraryDependencies += "org.scala-sbt" %% "scripted-plugin" % sbtVersion.value
+addSbtPlugin("com.scalawilliam.esbeetee" % "sbt-vspp" % "0.4.11")

readme.md

@@ -15,6 +15,11 @@ Add following line into `project/plugins.sbt` (latest version is available next
 addSbtPlugin("org.scalameta" % "sbt-scalafmt" % PLUGIN_VERSION)
 ```
 
+If the above does not work, in enterprise environments, try:
+```sbt
+libraryDependencies += "org.scalameta" % "sbt-scalafmt_2.12_1.0" % PLUGIN_VERSION
+```
+
 ### [User documentation](https://scalameta.org/scalafmt/)
 Head over to [the user docs](https://scalameta.org/scalafmt/docs/installation.html#sbt) for instructions on how to install and use scalafmt.