Fix wrong 'nuget source add' command in example for deploying NuGet packages with CI/CD

doc/user/packages/nuget_repository/index.md

@@ -337,7 +337,7 @@ updated:
      stage: deploy
      script:
        - dotnet pack -c Release
-       - dotnet nuget add source "${CI_API_V4_URL}/${CI_PROJECT_ID}/packages/nuget/index.json" --name gitlab --username gitlab-ci-token --password $CI_JOB_TOKEN --store-password-in-clear-text
+       - dotnet nuget add source "${CI_API_V4_URL}/projects/${CI_PROJECT_ID}/packages/nuget/index.json" --name gitlab --username gitlab-ci-token --password $CI_JOB_TOKEN --store-password-in-clear-text
        - dotnet nuget push "bin/Release/*.nupkg" --source gitlab
      only:
        - master