Merge pull request #547 from scala-steward/update/sbt-mdoc-2.5.1

Update sbt-mdoc to 2.5.1

Author: mpilquist

project/plugins.sbt

@@ -4,4 +4,4 @@ addSbtPlugin("org.scala-native" % "sbt-scala-native" % "0.4.16")
 addSbtPlugin("org.portable-scala" % "sbt-scala-native-crossproject" % "1.3.2")
 addSbtPlugin("ch.epfl.scala" % "sbt-scalajs-bundler" % "0.21.1")
 addSbtPlugin("com.github.tkawachi" % "sbt-doctest" % "0.10.0")
-addSbtPlugin("org.scalameta" % "sbt-mdoc" % "2.4.0")
+addSbtPlugin("org.scalameta" % "sbt-mdoc" % "2.5.1")