[C#] chore: Fix readme & remove Nuget.Config (#1032)

## Linked issues

closes: #1000  (issue number)

## Details

Provide a list of your changes here. If you are fixing a bug, please
provide steps to reproduce the bug.

## Attestation Checklist

- [x] My code follows the style guidelines of this project

- I have checked for/fixed spelling, linting, and other errors
- I have commented my code for clarity
- I have made corresponding changes to the documentation (we use
[TypeDoc](https://typedoc.org/) to document our code)
- My changes generate no new warnings
- I have added tests that validates my changes, and provides sufficient
test coverage. I have tested with:
  - Local testing
  - E2E testing in Teams
- New and existing unit tests pass locally with my changes

dotnet/samples/README.md

@@ -41,9 +41,9 @@ There are a few ways to get the application up and running. The latest way is us
 > recommend creating and using a [Microsoft 365 Developer Program](https://developer.microsoft.com/microsoft-365/dev-program) account -
 > a free program to get your own dev environment sandbox that includes Teams.
 
-1. Press F5, or select the `Debug > Start` Debugging menu in Visual Studio. If step 3 was completed correctly then this should launch a browser.
-2. In the launched browser, select the `Add` button to load the app in Teams.
-3. This should redirect you to a chat window with the bot.
+5. Press F5, or select the `Debug > Start` Debugging menu in Visual Studio. If step 3 was completed correctly then this should launch a browser.
+6. In the launched browser, select the `Add` button to load the app in Teams.
+7. This should redirect you to a chat window with the bot.
 </details>
 
 <details>