Update KaTeX to 0.10.0

Update KaTeX to 0.10.0

• Accompanying gitter-markdown-processor MR, https://gitlab.com/gitlab-org/gitter/gitter-markdown-processor/merge_requests/18

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• https://katex.org/docs/font.html#kinds-of-fonts-used
• https://github.com/KaTeX/katex-fonts/
• https://katex.org/docs/browser.html