docs: update Markdown equation elements

lib/node_modules/@stdlib/stats/base/dists/anglit/skewness/README.md

@@ -34,6 +34,11 @@ The [skewness][skewness] for an [anglit][anglit-distribution] random variable wi
 \mathop{\mathrm{skew}}\left( X \right) = 0
 ```
 
+<!-- <div class="equation" align="center" data-raw-text="\operatorname{skew}\left( X \right) = 0" data-equation="eq:anglit_skewness">
+    <img src="https://cdn.jsdelivr.net/gh/stdlib-js/stdlib@5f0b02c1b2aa3caaac38741589ab5a9c0483bcb7/lib/node_modules/@stdlib/stats/base/dists/anglit/skewness/docs/img/equation_anglit_skewness.svg" alt="Skewness for an anglit distribution.">
+    <br>
+</div> -->
+
 <!-- </equation> -->
 
 </section>

lib/node_modules/@stdlib/stats/base/dists/burr-type3/cdf/README.md

@@ -32,6 +32,11 @@ The [cumulative distribution function][cdf] for a [Burr (type III)][burr-distrib
 F(x; c, d) = (1 + x^{-c})^{-d}
 ```
 
+<!-- <div class="equation" align="center" data-raw-text="F(x; c, d) = (1 + x^{-c})^{-d}" data-equation="eq:burr_type3_cdf">
+    <img src="https://cdn.jsdelivr.net/gh/stdlib-js/stdlib@5f0b02c1b2aa3caaac38741589ab5a9c0483bcb7/lib/node_modules/@stdlib/stats/base/dists/burr-type3/cdf/docs/img/equation_burr_type3_cdf.svg" alt="Cumulative distribution function for a Burr (Type III) distribution.">
+    <br>
+</div> -->
+
 <!-- </equation> -->
 
 where `c > 0` is the first shape parameter and `d > 0` is the second shape parameter.

lib/node_modules/@stdlib/stats/base/dists/log-logistic/variance/README.md

@@ -29,9 +29,14 @@ The [variance][variance] for a [log-logistic][log-logistic-distribution] random
 <!-- <equation class="equation" label="eq:log_logistic_variance" align="center" raw="\operatorname{Var}\left[ X \right] = \alpha^2 \left( \frac{2b}{\sin 2b} - \frac{b^2}{\sin^2 b} \right), \quad b = \frac{\pi}{\beta}" alt="Variance for a log-logistic distribution."> -->
 
 ```math
-\operatorname{Var}\left[ X \right] = \alpha^2 \left( \frac{2b}{\sin 2b} - \frac{b^2}{\sin^2 b} \right), \quad b = \frac{\pi}{\beta}
+\mathop{\mathrm{Var}}\left[ X \right] = \alpha^2 \left( \frac{2b}{\sin 2b} - \frac{b^2}{\sin^2 b} \right), \quad b = \frac{\pi}{\beta}
 ```
 
+<!-- <div class="equation" align="center" data-raw-text="\operatorname{Var}\left[ X \right] = \alpha^2 \left( \frac{2b}{\sin 2b} - \frac{b^2}{\sin^2 b} \right), \quad b = \frac{\pi}{\beta}" data-equation="eq:log_logistic_variance">
+    <img src="https://cdn.jsdelivr.net/gh/stdlib-js/stdlib@5f0b02c1b2aa3caaac38741589ab5a9c0483bcb7/lib/node_modules/@stdlib/stats/base/dists/log-logistic/variance/docs/img/equation_log_logistic_variance.svg" alt="Variance for a log-logistic distribution.">
+    <br>
+</div> -->
+
 <!-- </equation> -->
 
 where `b = π/β`.