Docs: Typo Fix (#4570)

Corrected "The aim of this classifier is to detect bugs which should be documented for developers." to "The aim of this classifier is to detect bugs that should be documented for developers.

This pull request addresses a minor typo found in repository. The typo has been corrected to improve clarity and maintain the quality of the documentation.

This change is purely cosmetic and does not affect functionality.

README.md

@@ -31,7 +31,7 @@ Data generated by BugBug to train the models can be used independently from BugB
 
 - **defect** - Bugs on Bugzilla aren't always bugs. Sometimes they are feature requests, refactorings, and so on. The aim of this classifier is to distinguish between bugs that are actually bugs and bugs that aren't. The dataset currently contains 2110 bugs, the accuracy of the current classifier is ~93% (precision ~95%, recall ~94%).
 
-- **devdocneeded** - The aim of this classifier is to detect bugs which should be documented for developers.
+- **devdocneeded** - The aim of this classifier is to detect bugs that should be documented for developers.
 
 - [**needsdiagnosis**](https://github.com/webcompat/webcompat.com/blob/main/docs/ml-process.md) - The aim of this classifier is to detect issues that are likely invalid and don't need to be diagnosed for webcompat use case.