Improve quick-start template process at the runtime to use the content files as includes

[jeradrutnam]

Purpose

$subject

Below is the new way of adding quick starts. Improvement is made to support include supporting for reusability.

---
template: templates/quick-start.html
---

<script>
  const meta = {
    what_you_will_learn: [
      "You will learn this"
    ],
    prerequisites: [
      "About 15 minutes"
    ],
    whats_next: [
      "Check this content"
    ]
  };
</script>

# Page Heading

Page Description - {{ product_name }} {{ product }} {{ base_path }}

[//] STEPS_START

## Step 1 Heading

Step Content Text Goes Here

## Step 2 Heading

Step Content Text Goes Here

[//] STEPS_END

Goals

Approach

Release note

Documentation

Security checks

• [] Followed secure coding standards in http://wso2.com/technical-reports/wso2-secure-engineering-guidelines?
• [] Ran FindSecurityBugs plugin and verified report?
• [] Confirmed that this PR doesn't commit any keys, passwords, tokens, usernames, or other secrets?

Related PRs

Test environment