Setup Mermaid for Docusaurus

[tcvan0707]

Issue This PR Addresses

Fixes issue #2960

Type of Change

• Bugfix: Change which fixes an issue
• New Feature: Change which adds functionality
• Documentation Update: Change which improves documentation
• UI: Change which improves UI

Description

This PR is going to set up Mermaid for our Docusaurus. The picture below is a sample to proof that Mermaid is working in our docs

Steps to test the PR

• Change the current directory to src/docs: cd src/docs/
• Run pnpm start
• Go to localhost:4631 on the web browser

Checklist

• Quality: This PR builds and passes our npm test and works locally
• Tests: This PR includes thorough tests or an explanation of why it does not
• Screenshots: This PR includes screenshots or GIFs of the changes made or an explanation of why it does not (if applicable)
• Documentation: This PR includes updated/added documentation to user exposed functionality or configuration variables are added/changed or an explanation of why it does not(if applicable)

[gitpod-io]

[cindyorangis]

I've been waiting for this! You have no idea.

After following your steps, I added

```mermaid
graph TD;
    A-->B;
    A-->C;
    B-->D;
    C-->D;
```

to src/docs/docs/overview.md just to test it out and it worked!

I can finally unblock #2880 now

[tcvan0707]

I've been waiting for this! You have no idea.

After following your steps, I added

```mermaid
graph TD;
    A-->B;
    A-->C;
    B-->D;
    C-->D;

to `src/docs/docs/overview.md` just to test it out and it worked! ![2022-03-09 12_52_11-Window](https://user-images.githubusercontent.com/36822198/157501472-b4e940b9-1a30-4295-8e48-1ff0e10bbfdd.png)

I can finally unblock #2880 now

If we want to make a graph, there is a keyword graph we have to specify, along with the TD is the direction where the graph will go, TD is Top Down I believe, I also tried LR (Left to Right) and RL (Right to Left). Hope this will help you!! 😊

[tpmai22]

@tcvan0707 thank you for throwing those information in. That absolutely help me if I want to contribute in the future !

[menghif]

Very useful!

[Kevan-Y]

Nice feature