fix: replace .english.md extension with .md

curriculum/challenges/english/10-coding-interview-prep/project-euler/problem-86-cuboid-route.md

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+---
+id: 5900f3c31000cf542c50fed5
+challengeType: 5
+title: 'Problem 86: Cuboid route'
+forumTopicId: 302200
+---
+
+## Description
+<section id='description'>
+
+A spider, S, sits in one corner of a cuboid room, measuring 6 by 5 by 3, and a fly, F, sits in the opposite corner. By travelling on the surfaces of the room the shortest "straight line" distance from S to F is 10 and the path is shown on the diagram.
+
+<img class="img-responsive center-block" alt="a diagram of a spider and fly's path from one corner of a cuboid room to the opposite corner" src="https://cdn-media-1.freecodecamp.org/project-euler/cuboid-route.png" style="background-color: white; padding: 10px;">
+
+However, there are up to three "shortest" path candidates for any given cuboid and the shortest route doesn't always have integer length.
+
+It can be shown that there are exactly 2060 distinct cuboids, ignoring rotations, with integer dimensions, up to a maximum size of M by M by M, for which the shortest route has integer length when M = 100. This is the least value of M for which the number of solutions first exceeds two thousand; the number of solutions when M = 99 is 1975.
+
+Find the least value of M such that the number of solutions first exceeds one million.
+
+</section>
+
+## Instructions
+<section id='instructions'>
+
+</section>
+
+## Tests
+<section id='tests'>
+
+```yml
+tests:
+  - text: <code>cuboidRoute()</code> should return a number.
+    testString: assert(typeof cuboidRoute() === 'number');
+  - text: <code>cuboidRoute()</code> should return 1818.
+    testString: assert.strictEqual(cuboidRoute(), 1818);
+
+```
+
+</section>
+
+## Challenge Seed
+<section id='challengeSeed'>
+
+<div id='js-seed'>
+
+```js
+function cuboidRoute() {
+
+  return true;
+}
+
+cuboidRoute();
+```
+
+</div>
+
+
+
+</section>
+
+## Solution
+<section id='solution'>
+
+```js
+// solution required
+```
+
+</section>