fix typo in example of heading-blank-lines

[northword]

document: https://github.com/platers/obsidian-linter/blob/master/docs/rules.md#heading-blank-lines
related: #219

Example: Empty line before header and after Yaml is removed with Empty Line Between Yaml and Header=true

Before:

---
key: value
---
# Header
Paragraph here...
After:

---
key: value
---
# Header

Paragraph here...

when Empty Line Between Yaml and Header=true, it should be

> ---
> key: value
> ---
>
> # Header
> 
> Paragraph here...

only when Empty Line Between Yaml and Header=false, it is

> ---
> key: value
> ---
> # Header
> 
> Paragraph here...

In addition, a blank line has been added after the YAML in before to better illustrate that the blank line between the YAML and the title will be removed when Empty Line Between Yaml and Header=false.

[pjkaufman]

If the indentation is fixed as requested by the CI, I am fine with approving this.

[northword]

Thanks, the question has been revised, please review again.