[feature] Pull docs from OpenWISP modules to create a unified documentation Website #107

[pandafy]

Closes #107

[pandafy]

TODOS

• [x] Generate symbolic link for stable version of each module
• [x] Support passing module details from environment variable
• [x] Build documentation for 22.05 separately. This will automatically fix duplicated menu entries.
• [x] Allow building only specific versions using make file
• [x] Fix the QA check for broken links - ignore 404 errors for pages that are only added in dev version
• [x] Verify PDFs open correctly
• [x] Generate canonical tag which ls present on the stable version.