fix. 修复mathjax无法显示的问题

[soundofautumn]

使用前端渲染数学公式时会出现以下错误 :23 Uncaught ReferenceError: MathJax is not defined

相关代码：

    <script>
        MathJax.Hub.Config({
            menuSettings: {
                zoom: "None"
            },
            showMathMenu: false,
            jax: ["input/TeX", "output/CommonHTML"],
            extensions: ["tex2jax.js"],
            TeX: {
                extensions: ["AMSmath.js", "AMSsymbols.js"],
                equationNumbers: {
                    autoNumber: "AMS"
                }
            },
            tex2jax: {
                inlineMath: [["\\(", "\\)"]],
                displayMath: [["\\[", "\\]"]]
            }
        });
    </script>

应该是异步导致的，取消异步后显示正常