Document more remarks about the diagnostics CLI tools

[sywhang]

Summary

Checks rest of the checkboxes from dotnet/diagnostics#1737

• Tools targeting x86 need to be started using the x86 host.
• Tools need to share a TMPDIR environment variable value with the target application.
• Tools need run as same user as the target application to access diagnostic pipes

Part of dotnet/diagnostics#515.

[josalem]

We may want to add a note that says failing to do meet these requirements can result in <insert the error message> since the error message doesn't necessarily imply the problem in this case.

[sdmaclea]

It is not clear how to do this. It might be nice to have more detailed instructions somewhere. Having two versions of the tool on Windows is a bit difficult. I was using the same tool but executing it with the x86 runtime by pointing dotnet at dotnet-dump.dll. It is a bit awkward experience.

This also affects arm32 when analyzing cross dumps on Windows. So you currently need a 32bit dotnet tool process to debug a 32 bit target process or 32 bit dump.

So I guess you would see a similar problem on a arm64 host running a arm32 process. Although I can't say I have seen that problem. So it might not exist.

[sywhang]

Thanks for the feedback Steve.

AFAIK the easiest/pain-free way for the customers to do this would be to just use the single-file versions of these apps which is why I added the remark here (the most natural thing to do after reading this comment would be to just click the x86 link above).

[sdmaclea]

Its OK to leave as is, I didn't really get my bearings. You could consider something like this ...

Suggested change

	> To use `dotnet-counters` on an x86 app, you need a corresponding x86 version of the tool.
	> To use `dotnet-counters` on an win-x86 app, you need a corresponding [win-x86](https://aka.ms/dotnet-counters/win-x86) direct download version of the tool.

[sdmaclea]

LGTM May want to consider comment regarding x86 and 32-bit processes.