message: docs(license): notes on CSF
  ### Related Ticket(s)
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  ### Description
  Adds implementation notes on our usage of Storybook Component Story Format (CSF) so that new developers can quickly understand how it works.
  ### Changelog
  **New**
  Implementation notes on our usage of Storybook Component Story Format (CSF).
diff: @@ -387,6 +387,16 @@ Both of above use [RTLCSS](https://rtlcss.com) to generate the RTL version. RTLC
  How to use the RTL version of CSS can be seen at [the usage documentation](https://github.com/carbon-design-system/carbon-for-ibm-dotcom/blob/v1.15.0/packages/web-components/docs/enable-rtl.md).
  +## Storybook CSF integration
  +
  +Storybook introduced a new story format in `5.x` timeframe, called Component Story Format (CSF). It makes stories an ECMAScript import, that is great for reusing stories.
  +
  +Unfortunately, knobs still require imperative API embedded in stories, which means as soon as we define knobs in stories any code calling stories depends on such knobs.
  +
  +To make sure that we can reuse stories for unit tests without depending on knobs, we define knobs somewhere outside stories, which is, in story parameters (`parameters.knobs`), like [here](https://github.com/carbon-design-system/carbon-for-ibm-dotcom/blob/v1.15.0/packages/web-components/src/components/card/__stories__/card.stories.ts#L116-L146). Such `parameters.knobs` is evaluated in a [global story decorator](https://github.com/carbon-design-system/carbon-for-ibm-dotcom/blob/v1.15.0/packages/web-components/.storybook/decorator-knobs.ts) and put into `parameters.props`, so that stories can refer to like [this](https://github.com/carbon-design-system/carbon-for-ibm-dotcom/blob/v1.15.0/packages/web-components/src/components/card/__stories__/card.stories.ts#L26).
  +
  +In this way, test can specify its own `parameters.props`, without being interfered by knobs. An example can be found [here](https://github.com/carbon-design-system/carbon-for-ibm-dotcom/blob/v1.15.0/packages/web-components/src/components/card/__tests__/card.test.ts#L14-L21).
  +
  ## License header
  We ensure that our source code has appropriate licence header, with two mechanisms:
  