Documentation updates

[martincostello]

I came across this project via a Google search, but it brought me to the repository not the NuGet package. There was no explicit link to the package anywhere in the README, so I had to manually go off and find it. These changes to the README should hopefully make it easier for people to get started in the future.

The included changes also:

• Add NuGet badges.
• Add namespace to first code snippet.
• Change dotnet to .NET.
• Change nuget to NuGet.
• Fix Visual Studio Code MarkdownLint warnings.

I haven't run the code to regenerate the documentation files from their source as:

1. I don't have make installed
2. The scripts are written in bash and I have a Windows computer

[JoshKeegan]

Hi @martincostello,
Thanks for taking the time to improve the docs. I'll run the generation again 👍 If you do ever want to contribute to the project again & need to run the build scripts, both make & bash can be installed on windows & work quite well. I've run these on windows myself previously using the version of bash that comes bundled with git, so they should still all work on windows.

I'll also split your changes to the CI badge file as that gets included in the .md that is published with each nuget package.