Create CI for automating documentation page

Currently, I manually run in my machine:

```ps1
dotnet build Murder.sln
.\tools\dotnet2md.ps1 ..\src\Murder\bin\Debug\net7.0
tools\publish.ps1
```

So it outputs the md files at `docs\src` and the html files at `docs\book`. We should rather have a GitHub action (or a bot?) that automatically generates the html files.