2.0 updates to Swagger tutorial (#4145)
* 2.0 updates to Swagger tutorial
* More edits
* Add missing wwwroot folder
* More edits
* More edits
* Update code comment
* Move UseMvc call to last invocation
* Update property name in JSON sample
* Convert UseMvcWithDefaultRoute() to UseMvc()
* Add Startup2.cs
* Simplify the .csproj file
* Adopt new WebHost pattern in Program.cs
* walk through --> walkthrough
* Remove unused controller
* Update images
* Remove unused controller
* More edits
* Wordsmithing
* Provide more detail in UI customization text
* Modify JSON sample
* Add keywords
* Implement Rick's suggestions
* Add cross platform instructions
* Update image
* Convert 2 sentences into list
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