fix: replace .english.md extension with .md

curriculum/challenges/english/10-coding-interview-prep/project-euler/problem-178-step-numbers.md

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+---
+id: 5900f41e1000cf542c50ff31
+challengeType: 5
+title: 'Problem 178: Step Numbers'
+forumTopicId: 301813
+---
+
+## Description
+<section id='description'>
+Consider the number 45656.
+It can be seen that each pair of consecutive digits of 45656 has a difference of one.
+A number for which every pair of consecutive digits has a difference of one is called a step number.
+A pandigital number  contains every decimal digit from 0 to 9 at least once.
+
+How many pandigital step numbers less than 1040 are there?
+</section>
+
+## Instructions
+<section id='instructions'>
+
+</section>
+
+## Tests
+<section id='tests'>
+
+```yml
+tests:
+  - text: <code>euler178()</code> should return 126461847755.
+    testString: assert.strictEqual(euler178(), 126461847755);
+
+```
+
+</section>
+
+## Challenge Seed
+<section id='challengeSeed'>
+
+<div id='js-seed'>
+
+```js
+function euler178() {
+
+  return true;
+}
+
+euler178();
+```
+
+</div>
+
+
+
+</section>
+
+## Solution
+<section id='solution'>
+
+```js
+// solution required
+```
+
+</section>