IBX-9006: Collaborative editing - REST API documentation

[julitafalcondusza]

Question	Answer
JIRA Ticket	(https://issues.ibexa.co/browse/IBX-9006)
Versions	4.6+

Collaborative editing - REST API documentation:

• [REST] Endpoint for obtaining the public link for collaboration session (https://issues.ibexa.co/browse/IBX-8738)
• [REST] Endpoint for initiating collaboration session (https://issues.ibexa.co/browse/IBX-8739)
• [REST] Endpoint for deleting collaboration session (https://issues.ibexa.co/browse/IBX-8744)
• [REST] Add input validation for create collaboration session endpoint (https://issues.ibexa.co/browse/IBX-9048)
• [REST] Endpoint for retrieving collaboration session details (https://issues.ibexa.co/browse/IBX-8745)
• [REST] Endpoint for updating participant scope (https://issues.ibexa.co/browse/IBX-8741)
• [REST] Endpoint for removing participant (https://issues.ibexa.co/browse/IBX-8742)
• [REST] Endpoint for listing participants (https://issues.ibexa.co/browse/IBX-8743)
• [REST] Endpoint for add participant (https://issues.ibexa.co/browse/IBX-9001)
• [REST] Endpoint for creating collaboration invitation (https://issues.ibexa.co/browse/IBX-8740)
• [REST] Endpoint to list users with their permissions to content item (https://issues.ibexa.co/browse/IBX-9002)

Checklist

• Text renders correctly
• Text has been checked with vale
• Description metadata is up to date
• Redirects cover removed/moved pages
• Code samples are working
• PHP code samples have been fixed with PHP CS fixer
• Added link to this PR in relevant JIRA ticket or code PR