revert contributing.md to simpler instructions

Author: tukib

CONTRIBUTING.md

@@ -10,24 +10,6 @@ This document builds on the [default contributing.md](https://github.com/comcode
 
 ### Creating tests
 
-1. For some module `foo.ts`, create a file `foo.test.ts` in the same directory.
-   - Tests must be within `/src`.
-   - `.tsx` `.mjs` `.jsx` and `.js` are also valid extensions.
-2. Import required jest utils from `@jest/globals`, and the module to be tested.
-3. Use `describe` to log what code is being tested and use `it` to describe a specification of the module.
-
-```ts
-/** @file criticalMathModule.test.ts */
-import { describe, expect, it } from "@jest/globals";
-import { isEven } from "./criticalMathModule";
-
-describe("criticalMathModule", () => {
-  // read as: it checks if numbers are even
-  it("checks if numbers are even", () => {
-    expect(isEven(1)).toBe(false);
-    expect(isEven(4)).toBe(true);
-  });
-});
-```
+Test files must be within `/src`, with a file name ending in `.test.<ext>`, where `<ext>` is one of `js` `mjs` `jsx` `ts` `tsx`.
 
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