Clean up README.md

[VictorioBerra]

Add link to Reddit for app creation.

I also removed some verbosity on how to install a NuGet. Most developers will know how to get the library and there are just too many ways to list them all out in the README. (dotnet add package, Install-Package, VS-GUI, JetBrains Rider GUI, etc.) No point in listing all that out.

I also cleaned up some text around the "binding to a refresh token" stuff since there really is no binding to a refresh token, the access token is refreshed using the refresh token. Its OAuth.