Support Mathjax version 4

Documentation corrections after review (auch)

Author: albert-github

src/config.xml

@@ -2856,7 +2856,7 @@ For example for MathJax version 4 (see https://docs.mathjax.org/en/v4.0/input/te
 \verbatim
 MATHJAX_EXTENSIONS     = units
 \endverbatim
-Note that for Matjhax version 4 quite a few extensions are already automatically loaded.
+Note that for Mathjax version 4 quite a few extensions are already automatically loaded.
 ]]>
       </docs>
     </option>