Updates to markdown/html handling + deps and project

[jerdog]

Had some issues trying to convert docFX to Docusaurus (v3.7) and made some updates to some dependencies, project version, and HTML/markdown handling.

• Update Log73 package to version 0.8.0-preview2
• Enable nullable reference types
• Set language version to C# 11.0
• Add implicit usings support
• Update handling of HTML and markdown

Project configuration:

• Set PackAsTool and ToolCommandName for CLI distribution
• Add package license (MIT) and repository URL
• Set package output path to ./nupkg
• Add package description

Tested build on MacOS Sequoia 15.4.1, Apple Silicon

dotnet publish -c Release -r osx-x64 --self-contained true -p:PublishSingleFile=true

Output:

Restore complete (0.5s)
  DocFxMarkdownGen succeeded (2.4s) → bin/Release/net6.0/osx-x64/publish/

Build succeeded in 3.1s

./DocFxMarkdownGen output:

DocFxMarkdownGen v0.4.2+4af5cf9600a9a8a166262982a04665d270f55ab4 running...
Info  Read all YAML in 1710ms.
Info  Generating and writing markdown...
Info  Generated markdown in 1406ms.

[philpax]

Hi! I'm not the maintainer of this project, but I tried out this PR to see if it would fix #19.

Unfortunately, I think it's unlikely this PR will be merged in its current state: it makes too many changes in one commit, resulting in a very large diff that's difficult to review. As a casual observer, I found it hard to discern the specific changes introduced by the PR. I would suggest breaking it up into multiple, smaller commits, each focusing on a single, isolated change. This would allow the maintainer to assess each change individually.

As it stands, it feels like a significant rewrite. Sorry to be the bearer of bad news!