Updated testcase documentation

[OsirisTerje]

The issue nunit/nunit#815 was documented for the Ignore attribute in #172, but it should also be updated for the TestCase, so this does that.

[Copilot]

Pull Request Overview

This PR adds documentation for the proper usage of named parameters with the TestCase attribute in NUnit, specifically addressing issue #815. The documentation clarifies how to correctly use Ignore, Explicit, and Category parameters to avoid accidentally applying them to the entire test fixture instead of individual test cases.

• Adds comprehensive examples and warnings about correct vs incorrect syntax for TestCase attribute named parameters
• Includes code examples demonstrating proper usage of Ignore, Explicit, and Category parameters
• Removes unused using statements from the examples file

Reviewed Changes

Copilot reviewed 2 out of 4 changed files in this pull request and generated 1 comment.

File	Description
TestCaseAttributeExamples.cs	Removes unused imports and adds example methods for TestCase with Ignore, Explicit, and Category parameters
testcase.md	Adds detailed documentation section explaining proper syntax for named parameters and common pitfalls

---

_{Tip: Customize your code reviews with copilot-instructions.md. Create the file or learn how to get started.}

[SeanKilleen]

@OsirisTerje Actually I'm going to go ahead and make some small language fixes which I don't think you'll mind, rather than give you a bunch of review comments to address

[SeanKilleen]

@OsirisTerje I've made some commits with edits. Assuming you agree with them, this is good to merge now. Feel free to edit anything you don't like 👍

[OsirisTerje]

Thanks @SeanKilleen , really appreciate it!