Merge pull request #113 from scala-steward/update/sbt-mdoc-2.2.9

Update sbt-mdoc to 2.2.9

Author: EmergentOrder

project/plugins.sbt

@@ -7,4 +7,4 @@ addSbtPlugin("ch.epfl.scala" % "sbt-scalafix" % "0.9.20")
 addSbtPlugin("org.scalameta" % "sbt-scalafmt" %  "2.4.2")
 addSbtPlugin("org.xerial.sbt" % "sbt-sonatype" % "3.9.4")
 addSbtPlugin("com.jsuereth" % "sbt-pgp" % "2.0.1")
-addSbtPlugin("org.scalameta" % "sbt-mdoc" % "2.2.8" )
+addSbtPlugin("org.scalameta" % "sbt-mdoc" % "2.2.9" )