OCCT documentation build-time dependency notice

Mathematical expressions in the generated OCCT documentation are converted to
inline SVG during the publishing build with MathJax 4.1.3 and the MathJax New
Computer Modern font package. The browser does not download or execute MathJax.

MathJax and its New Computer Modern font package are distributed under the
Apache License 2.0. A copy of that license is provided in this directory.