Addon-docs: Generalize Description doc block

[shilman]

Storybook's Description block should be framework-independent, similar to how props tables were generalized in #8123:

<Description of={MyComponent} />

Framework configuration:

import { addParameters } from '@storybook/client-api';

addParameters({
  docs: {
    extractDescription: (comp) => ...
  }
});

[shilman]

Olé!! I just released https://github.com/storybookjs/storybook/releases/tag/v5.3.0-alpha.32 containing PR #8590 that references this issue. Upgrade today to try it out!

You can find this prerelease on the @next NPM tag.

Closing this issue. Please re-open if you think there's still more to do.

[shilman]

Hurrah!! I just released https://github.com/storybookjs/storybook/releases/tag/v5.3.0-alpha.39 containing PR #8718 that references this issue. Upgrade today to try it out!

You can find this prerelease on the @next NPM tag.