Bump Markdig from 0.31.0 to 0.39.1

Bumps [Markdig](https://github.com/xoofx/markdig) from 0.31.0 to 0.39.1.
- [Release notes](https://github.com/xoofx/markdig/releases)
- [Changelog](https://github.com/xoofx/markdig/blob/master/changelog.md)
- [Commits](xoofx/markdig@0.31.0...0.39.1)

---
updated-dependencies:
- dependency-name: Markdig
  dependency-type: direct:production
  update-type: version-update:semver-minor
...

Signed-off-by: dependabot[bot] <support@github.com>

FlightSimulator/FlightSimulator.csproj

@@ -40,7 +40,7 @@
 
   <ItemGroup>
     <PackageReference Include="BoardManager" Version="1.2.6" />
-    <PackageReference Include="Markdig" Version="0.31.0" />
+    <PackageReference Include="Markdig" Version="0.39.1" />
     <PackageReference Include="MenuLibrary" Version="1.1.24" />
     <PackageReference Include="Microsoft.Web.LibraryManager.Build" Version="2.1.175" />
     <PackageReference Include="SimListener" Version="1.0.27" />