[FEATURE] Support Typora-style mermaid markdown rendering

[ClSlaid]

Describe the feature you want

• use typora-style mermaid markdown rending.
  Currently, most Hugo themes use short-codes as their way of importing multimedia content, and it does useful and convenient.
  However, as a visual studio code user (or markdown preview enhanced user, more precisely), shortcodes are not working in its editor; Typora uses the following syntax to import mermaid graphs.

```mermaid
#mermaid diagram scripts
```    e.g.

Then the editor will directly render them into graphs, what you see is what you got.

What if the theme could directly render such syntax of markdown text? then we needn't search through the whole text and replace them one by one.

[ClSlaid]

I've tried adding such a feature into Hugo-theme-even in February, however, the author seems to have abandoned the project and did not take even a look into my pull request, maybe the change in the PR may be of help to you...

[khusika]

is this related to the 3rd party markdown editor?

[ClSlaid]

is this related to the 3rd party markdown editor?

Not at all, I mean if the theme could render mermaid code blocks as mermaid shortcodes, it'll be of convenience.

[khusika]

Not at all, I mean if the theme could render mermaid code blocks as mermaid shortcodes, it'll be of convenience.

Did you mean converting FeelIt default codeblock?

from

{{< mermaid >}}
{{< /mermaid >}}

into

```mermaid

[ClSlaid]

Not at all, I mean if the theme could render mermaid code blocks as mermaid shortcodes, it'll be of convenience.

Did you mean converting FeelIt default codeblock?

from

{{< mermaid >}}
{{< /mermaid >}}

into

```mermaid

Yes, to be more precise, I mean treat

```mermaid

as

{{ < mermaid > }}
{{ </mermaid>}}