Controller name customization

[IPdotSetAF]

fixed the bug mentioned in #176 (controller name issue with URL Helper).
added Swagger fix in readme file

[what-the-diff]

PR Summary

• Incorporation of Conventional Routing NuGet Package
  A new piece of code was added so that we may effectively utilize the Swashbuckle.AspNetCore.SwaggerGen.ConventionalRouting NuGet Package. This is a tool that is able to streamline the way we route and organize requests within our application.

• Modification in DNTCaptchaApiProvider.cs File
  Within the DNTCaptchaApiProvider.cs file, alterations have been made to the way the controllerName variable behaves. If the _captchaOptions.CaptchaImageControllerNameTemplate is not left vacant, the controllerName variable will now utilize its value. This change provides better flexibility and control relating to Captcha image functions in the system.