Add `tilde` combining character to documentation

[manuelfuenmayor]

I've noticed that tilde combining character is not listed in AsciiMath documentation:

tilde x ->

I think it would be helpful to do so 👍.

Thanks!

[archiepaulson]

mathcal should be there too. I accidentally discovered that my latex \mathcal{E} works in asciimath, which is often used for emf (aka source voltage) in circuits.

[drlippman]

mathcal is a longhand equivalent to the cc font command which is already documented. But perhaps it would make sense to add a TeX alt column for the font commands.

Any suggestions for improving the asciimath.org documentation would be better added as an issue on https://github.com/asciimath/asciimath.github.io

[drlippman]

Got these added