mdoc v0.4.1

• Implement mdoc:silent modifier #71 by @olafurpg
• Preseve original formatting including trailing statement comments #70 by @olafurpg
• Fix watch mode and aggregate exit code #69 by @olafurpg
• Improve link hygiene #68 by @olafurpg
• Add ScastieModifier #59 by @gabro

mdoc is now used to generate scalafmt.org https://scalameta.org/scalafmt/docs/introduction.html
The fixes in this release are to unblock the websites for scalafix and scalameta