docs: Clarify how to enable math equations (#10894)

Co-authored-by: Sébastien Lorber <[email protected]>

Author: waldyrious

website/docs/guides/markdown-features/markdown-features-math-equations.mdx

@@ -10,9 +10,11 @@ import BrowserWindow from '@site/src/components/BrowserWindow';
 
 Mathematical equations can be rendered using [KaTeX](https://katex.org).
 
+See [below](#configuration) how to activate them.
+
 ## Usage {#usage}
 
-Please read [KaTeX](https://katex.org) documentation for more details.
+Please read the [KaTeX](https://katex.org) documentation for more details.
 
 ### Inline {#inline}