Webhook job event documentation should be updated

Problem to solve

As mentioned in https://gitlab.com/gitlab-com/account-management/commercial/netconomy/-/issues/14#note_742182791 the webhooks documentation page shows outdated schemas.

Proposal

For each hook type, make sure the schema in the docs matches the sample schema used for testing and the sample schema matches the actual schema.

• Push events
• Tag event
• Issue event
• Comment event
• Merge request event
• Wiki page event
• Pipeline event
• Job event
• Deployment event
• Group member event
• Subgroup event
• Feature flag event
• Release event