modified curly brackets

This is to avoid a page build failure (see: https://github.com/StatProofBook/StatProofBook.github.io/wiki/Using-LaTeX-and-MathJax#things-to-avoid).

Author: JoramSoch

P/dir-ep.md

@@ -131,7 +131,7 @@ $$
 The [probability density function of the gamma distribution](/P/gam-pdf) is given by
 
 $$ \label{eq:Gam-pdf}
-\mathrm{Gam}(x; a, b) = \frac{{b}^{a}}{\Gamma(a)} \, x^{a-1} \, \exp[-b x] \quad \text{for} \quad x > 0 \; .
+\mathrm{Gam}(x; a, b) = \frac{ {b}^{a} }{\Gamma(a)} \, x^{a-1} \, \exp[-b x] \quad \text{for} \quad x > 0 \; .
 $$
 
 Consider the [gamma random variables](/D/gam)
@@ -194,4 +194,4 @@ $$ \label{eq:Dir-EP-qed}
 \varphi_i = \int_0^\infty \prod_{j \neq i} \left( \frac{\gamma(\alpha_j,q_i)}{\Gamma(\alpha_j)} \right) \cdot \frac{q_i^{\alpha_i-1} \exp[-q_i]}{\Gamma(\alpha_i)} \, \mathrm{d}q_i \; .
 $$
 
-In other words, the [exceedance probability](/D/prob-exc) for one element from a [Dirichlet-distributed](/D/dir) [random vector](/D/rvec) is an integral from zero to infinity where the first term in the integrand conforms to a product of [gamma](/D/gam) [cumulative distribution functions](/D/cdf) and the second term is a [gamma](/D/gam) [probability density function](/D/pdf).
+In other words, the [exceedance probability](/D/prob-exc) for one element from a [Dirichlet-distributed](/D/dir) [random vector](/D/rvec) is an integral from zero to infinity where the first term in the integrand conforms to a product of [gamma](/D/gam) [cumulative distribution functions](/D/cdf) and the second term is a [gamma](/D/gam) [probability density function](/D/pdf).