docs: remove equation markup

Signed-off-by: Philipp Burckhardt <pburckhardt@outlook.com>

Author: Planeshifter

lib/node_modules/@stdlib/stats/incr/nanvariance/README.md

@@ -32,10 +32,6 @@ The [unbiased sample variance][sample-variance] is defined as
 s^2 = \frac{1}{n-1} \sum_{i=0}^{n-1} ( x_i - \bar{x} )^2
 ```
 
-<!-- <div class="equation" align="center" data-raw-text="s^2 = \frac{1}{n-1} \sum_{i=0}^{n-1} ( x_i - \bar{x} )^2" data-equation="eq:unbiased_sample_variance">
-    <img src="https://cdn.jsdelivr.net/gh/stdlib-js/stdlib@49d8cabda84033d55d7b8069f19ee3dd8b8d1496/lib/node_modules/@stdlib/stats/incr/variance/docs/img/equation_unbiased_sample_variance.svg" alt="Equation for the unbiased sample variance.">
-    <br>
-</div> -->
 
 <!-- </equation> -->