fix: replace .chinese.md extension with .md

curriculum/challenges/chinese/10-coding-interview-prep/project-euler/problem-209-circular-logic.md

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+---
+id: 5900f43e1000cf542c50ff4f
+challengeType: 5
+title: 'Problem 209: Circular Logic'
+videoUrl: ''
+localeTitle: 问题209：循环逻辑
+---
+
+## Description
+<section id="description"> k输入二进制真值表是从k个输入位（二进制数字，0 [假]或1 [真]）到1个输出位的映射。例如，逻辑AND和XOR函数的2输入二进制真值表是： <p> x y x AND y000010100111x y x XOR y000011101110多个6输入二进制真值表τ满足公式</p><p>所有6位输入（a，b，c，τ，a，b，c，d，e，f）和τ（b，c，d，e，f，一个XOR（b和c））= 0 d，e，f）？ </p></section>
+
+## Instructions
+<section id="instructions">
+</section>
+
+## Tests
+<section id='tests'>
+
+```yml
+tests:
+  - text: <code>euler209()</code>应该返回15964587728784。
+    testString: assert.strictEqual(euler209(), 15964587728784);
+
+```
+
+</section>
+
+## Challenge Seed
+<section id='challengeSeed'>
+
+<div id='js-seed'>
+
+```js
+function euler209() {
+  // Good luck!
+  return true;
+}
+
+euler209();
+
+```
+
+</div>
+
+
+
+</section>
+
+## Solution
+<section id='solution'>
+
+```js
+// solution required
+```
+
+/section>