This rule is triggered when the symbols used in the document for emphasis do not
match the configured emphasis style:

```markdown
*Text*
_Text_
```

To fix this issue, use the configured emphasis style throughout the document:

```markdown
*Text*
*Text*
```

The configured emphasis style can be a specific symbol to use (`asterisk`,
`underscore`) or can require all emphasis matches the first emphasis
(`consistent`).

Note: Emphasis within a word is restricted to `asterisk` in order to avoid
unwanted emphasis for words containing internal underscores like_this_one.

Rationale: Consistent formatting makes it easier to understand a document.