Remove examples from civictheme_starter_kit

These are the examples:

https://github.com/civictheme/monorepo-drupal/tree/develop/web/themes/co...
https://github.com/civictheme/monorepo-drupal/tree/develop/web/themes/co...
https://github.com/civictheme/monorepo-drupal/tree/develop/web/themes/co...

We have had reports that these have ended up in production sites which was not their intent.
Aside from the problems with the old twig namespaces being used and breaking newly created sub-themes.

As a workaround, please delete the following directories from your new sub-theme manually (unless you have added some code changes):

1. components/01-atoms/demo-button
2. components/02-molecules/navigation-card
3. components/03-organisms/header

We will address this issue in code soon.

PR: https://github.com/civictheme/monorepo-drupal/pull/1392

Removed the example override components from the starterkit. These components were added to help a developer understand the ways in which a custom component can be created, however we have seen that sometimes these components are not removed when creating an actual theme, and since the 1.11 upgrade, have not been properly maintained.

The more appropriate place for examples would be either in documentation, or a separate folder / repo specifically designed for showing examples, rather than the actual starter kit.

Before release we need new documentation explaining overrides of SDC components. The examples were misleading with the change in components.

Think we should also add link to this docs at the top of the slack channel.