fix: replace .english.md extension with .md

curriculum/challenges/english/10-coding-interview-prep/project-euler/problem-222-sphere-packing.md

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+---
+id: 5900f44b1000cf542c50ff5d
+challengeType: 5
+title: 'Problem 222: Sphere Packing'
+forumTopicId: 301865
+---
+
+## Description
+<section id='description'>
+What is the length of the shortest pipe, of internal radius 50mm, that can fully contain 21 balls of radii 30mm, 31mm, ..., 50mm?
+
+Give your answer in micrometres (10-6 m) rounded to the nearest integer.
+</section>
+
+## Instructions
+<section id='instructions'>
+
+</section>
+
+## Tests
+<section id='tests'>
+
+```yml
+tests:
+  - text: <code>euler222()</code> should return 1590933.
+    testString: assert.strictEqual(euler222(), 1590933);
+
+```
+
+</section>
+
+## Challenge Seed
+<section id='challengeSeed'>
+
+<div id='js-seed'>
+
+```js
+function euler222() {
+
+  return true;
+}
+
+euler222();
+```
+
+</div>
+
+
+
+</section>
+
+## Solution
+<section id='solution'>
+
+```js
+// solution required
+```
+
+</section>