Add some documentation around [Culture] attribute (#3296)

* Add a section on culture-sensitive attributes to attributes.md.

* Add culture.md under `test-authoring/` (cribbing from https://docs.nunit.org/articles/nunit/writing-tests/attributes/setculture.html).
Also mention `[SetUICulture]` in attributes.md.

Author: andrewimcclement

docs/docs/comparison/attributes.md

@@ -59,3 +59,10 @@ Here are TUnit's equivalent attributes to other test frameworks.
 | [Category] | [Trait("Category","")] | [Category] | [TestCategory] |
 | [Property] | [Trait]                | [Property] | [TestProperty] |
 
+## Culture-sensitive Attributes
+
+| TUnit              | xUnit | NUnit                  | MSTest |
+|--------------------|-------|------------------------|--------|
+| [Culture("en-US")] | -     | [SetCulture("en-US")]  | -      |
+| -                  | -     | [Culture("en-US")]     | -      |
+| -                  | -     | [SetUICulture("en-US") | -      |

docs/docs/test-authoring/culture.md

@@ -0,0 +1,28 @@
+# Culture
+
+The `[Culture]` attribute is used to set the [current Culture](https://learn.microsoft.com/en-us/dotnet/api/system.globalization.cultureinfo.currentculture) for the duration of a test. It may be specified at the level of a test, fixture or assembly.
+The culture remains set until the test or fixture completes and is then reset to its original value.
+
+Specifying the culture is useful for comparing against expected output
+that depends on the culture, e.g. decimal separators, etc.
+
+Only one culture may be specified. If you wish to run the same test under multiple cultures,
+you can achieve the same result by factoring out your test code into a private method
+that is called by each individual test method.
+
+## Examples
+
+```csharp
+using TUnit.Core;
+
+namespace MyTestProject;
+
+public class MyTestClass
+{
+    [Test, Culture("de-AT")]
+    public async Task Test3()
+    {
+        await Assert.That(double.Parse("3,5")).IsEqualTo(3.5);
+    }
+}
+```