Replace file destination instructions for OpenAPI build-time documentation so projects can build correctly

[sander1095]

Fixes #34508

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aspnetcore/fundamentals/openapi/aspnetcore-openapi.md	Generate OpenAPI documents

[captainsafia]

@sander1095 What operating system did you observe these issues on? When this doc was written we observed that ./ wasn't resilient to path handling in Windows.

[sander1095]

Hi @captainsafia !

I'm running on Windows 11. You're correct, when running on Ubuntu (via WSL), ./ does work.

However, this means the docs should be updated:

• to either reflect the fact that Windows and linux needs different paths, OR
• the ./ needs to be replaced with . , which works both on Windows and Ubuntu (WSL).

This PR does the latter. I do not have a mac available to test this on. I believe we should advocate for a single solution that works for all OS's, as teams can use multiple OS's :).

I remember you having a mac? If this works on your machine, would you consider accepting this approach? If you'd like me to take a different path, let me know!

[wadepickett]

Just a side note with a verification point:
I just tested it on Windows 11 Enterprise v 10.0.26100 + .NET SDK 9.0.102 using the sample for this doc: https://github.com/dotnet/AspNetCore.Docs/tree/3b6e82c616db6bfa0ec5899c268b02fc001b6d99/aspnetcore/fundamentals/openapi/samples/9.x/WebMinOpenApi

It compiled, no build error for that particular setup using either:
<OpenApiDocumentsDirectory>./</OpenApiDocumentsDirectory>
or
<OpenApiDocumentsDirectory>.</OpenApiDocumentsDirectory>

[Rick-Anderson]

I found that here. See #33361