Merge pull request #242 from sourcegraph/renovate/org.scalameta-sbt-mdoc-2.x

Update dependency org.scalameta:sbt-mdoc to v2.2.21

Author: olafurpg

project/plugins.sbt

@@ -2,7 +2,7 @@ addSbtPlugin("org.scalameta" % "sbt-native-image" % "0.3.0")
 addSbtPlugin("com.geirsson" % "sbt-ci-release" % "1.5.7")
 addSbtPlugin("com.eed3si9n" % "sbt-buildinfo" % "0.10.0")
 addSbtPlugin("org.scalameta" % "sbt-scalafmt" % "2.3.4")
-addSbtPlugin("org.scalameta" % "sbt-mdoc" % "2.2.19")
+addSbtPlugin("org.scalameta" % "sbt-mdoc" % "2.2.21")
 addSbtPlugin("ch.epfl.scala" % "sbt-scalafix" % "0.9.27")
 addSbtPlugin("com.thesamet" % "sbt-protoc" % "1.0.0")
 addSbtPlugin("ch.epfl.scala" % "sbt-bloop" % "1.4.8-17-3eab1f80")