Build Capact website using documents from external repositories

[pkosiec]

Description

For every build (from capactio/capact or capactio/website):

1. Get docs from all source repositories (currently just capactio/capact).
   1. Probably we need to clone the repos - and clone release branches as well, to have docs for older Capact versions.
   2. We can limit ourselves to just 3 last release branches
2. Clone website and put the docs inside docs directory
3. Build and publish the website

AC

Configure CI for:

• Capact repo:
  * Capact Main branch: dispatch event to website to trigger build
  * PR build for Capact main branch:
  * Build minimal version of website just to preview the documents from a given repo (e.g. capact)
• Website
  * Website main branch build: allow to trigger it manually
  * Get docs from all source repos
  * Include docs releases (release branches)
  * Exclude internal directory from Capact (with proposals and investigations)
  * Do it as simple as possible
  * Enable running it locally (e.g. with npm start)
  * Website PR: similar to main branch
• Make sure the solution is scalable. We will have multiple source repositories in the future.
• Support Capact versioning - Versioning
  * Remember about best practices described there
• For now, we don’t remove previous doc releases

Additional scope

• Remove ToC from documents

Reason

To make it easier, we went with a simple solution to keep documentation with website content. However, this solution doesn't scale well. Ideally, it would be good to keep documentation close to actual code/component, especially if we will have multiple repositories in the future.