Crate nekolib_doc::poc::katex_support

$\KaTeX$ support

Renders $`119\cdot 2^{23}+1`$ into $119\cdot 2^{23}+1$, while $5\cdot 2^{25}+1$ into $5\cdot 2^{25}+1$. Also

```math
f(x) = \int_{-\infty}^\infty
\hat f(\xi)\,e^{2 \pi i \xi x}\, \mathrm{d}\xi
```

into:

f(x) = \int_{-\infty}^\infty
\hat f(\xi)\,e^{2 \pi i \xi x}\, \mathrm{d}\xi