docs: added the Welcome page for the Design System (Storybook)

[swapnilmmane]

Added the Welcome page for the Design System (Storybook)
Also included MDX file configuration to support writing plain docs, and added assets to the static directory to serve images and other resources.

Changes

In Storybook we can use MDX files to create plain documentation. To achieve this, we added the MDX file configuration in the Storybook setup:

const config: StorybookConfig = {
  stories: ["../docs/stories/**/*.mdx", "../src/**/*.stories.@(js|jsx|mjs|ts|tsx)"],
};

Additionally, to serve images and other static assets, we defined the following in the Storybook configuration:

staticDirs: ["../assets"],

How Has This Been Tested?

Tested manually.