Subscript is eaten by postprocessor

[JeppeKlitgaard]

Example:

```anki
id: 1636911985314
tags:
  - equation
---
 A [[Power Series]] is defined as a series of the form:
===
$$
∑\limits_{n=0}^∞ a_n (x-c)^n
$$

Where $c$ is the _centre_ of the series. It is often the case that $c=0$.
```

Produces:

<template>
	<p n="0">
		\(∑\limits_^∞ a_n (x-c)^n\)
	</p>
	<p>
		Where \(c \) is the <em>centre</em> of the series. It is often the case that \(c=0 \).
	</p>
</template>

[JeppeKlitgaard]

This is due to an expected side-effect of having the Markdown Attributes plugin enabled.

We should use the same rendering as Obsidian.