docs: remove unused definition

Signed-off-by: Athan <[email protected]>

Author: kgryte

lib/node_modules/@stdlib/stats/strided/sztest2/README.md

@@ -407,8 +407,6 @@ int main( void ) {
 
 <section class="links">
 
-[variance]: https://en.wikipedia.org/wiki/Variance
-
 [@stdlib/array/float32]: https://github.com/stdlib-js/stdlib/tree/develop/lib/node_modules/%40stdlib/array/float32
 
 [@stdlib/stats/base/ztest/alternatives]: https://github.com/stdlib-js/stdlib/tree/develop/lib/node_modules/%40stdlib/stats/base/ztest/alternatives