Update sbt-mdoc to 2.2.18 (#334)

Co-authored-by: Salar Rahmanian <[email protected]>

Author: scala-steward

project/plugins.sbt

@@ -2,7 +2,7 @@ addSbtPlugin("org.scalameta"      % "sbt-scalafmt"   % "2.4.0")
 addSbtPlugin("pl.project13.scala" % "sbt-jmh"        % "0.4.0")
 addSbtPlugin("com.eed3si9n"       % "sbt-buildinfo"  % "0.10.0")
 addSbtPlugin("org.scoverage"      % "sbt-scoverage"  % "1.6.1")
-addSbtPlugin("org.scalameta"      % "sbt-mdoc"       % "2.2.16")
+addSbtPlugin("org.scalameta"      % "sbt-mdoc"       % "2.2.18")
 addSbtPlugin("ch.epfl.scala"      % "sbt-bloop"      % "1.4.8")
 addSbtPlugin("com.eed3si9n"       % "sbt-unidoc"     % "0.4.3")
 addSbtPlugin("com.geirsson"       % "sbt-ci-release" % "1.5.5")