Updated TeX support (markdown)

TeX-support.md

@@ -5,10 +5,10 @@ You can write math by TeX. With $$ and $$$, write some equations.
 $$$ 1 + \frac{q^2}{(1-q)}+\frac{q^6}{(1-q)(1-q^2)}+\cdots = \prod_{j=0}^{\infty}\frac{1}{(1-q^{5j+2})(1-q^{5j+3})}, \quad\quad \text{for }\lvert q\rvert<1. $$$
 
 ## inline math
-This is $$\begin{Bmatrix}
+This $$\begin{Bmatrix}
    a & b \\
    c & d
-\end{Bmatrix}$$ a matrix
+\end{Bmatrix}$$ is a matrix
 ```
 
 ![image](https://user-images.githubusercontent.com/11307908/32276970-3d464576-bf54-11e7-8d67-79110dcffdd8.png)