Update mdoc, sbt-mdoc to 2.3.8

Author: 47erbot

project/plugins.sbt

@@ -7,7 +7,7 @@ addSbtPlugin("pl.project13.scala"        % "sbt-jmh"                  % "0.4.6")
 addSbtPlugin("com.github.sbt"            % "sbt-ci-release"           % "1.5.12")
 addSbtPlugin("com.47deg"                 % "sbt-microsites"           % "1.4.3")
 addSbtPlugin("org.scalameta"             % "sbt-scalafmt"             % "2.5.2")
-addSbtPlugin("org.scalameta"             % "sbt-mdoc"                 % "2.3.7")
+addSbtPlugin("org.scalameta"             % "sbt-mdoc"                 % "2.3.8")
 addSbtPlugin("de.heikoseeberger"         % "sbt-header"               % "5.10.0")
 addSbtPlugin("com.alejandrohdezma"       % "sbt-github"               % "0.11.11")
 addSbtPlugin("com.alejandrohdezma"       % "sbt-github-header"        % "0.11.11")