Merge branch 'mr-update-api-urls' into 'main'

docs/details/callbacks.mdx

docs/details/destination-management.mdx

docs/details/infrastructure-docs/sender.md

docs/details/infrastructure-docs/subscriber.md

docs/getting-started/authentication.mdx

docs/getting-started/event-log.mdx

docs/getting-started/first-steps.mdx

docs/receiving/download-submission.mdx

docs/receiving/notification.mdx

docs/responsibilities/get-destination.mdx

docs/sending/attachments.mdx

docs/sending/encrypt.mdx

docs/sending/query-status.mdx

docs/sending/start-submission.mdx

docs/sending/submit.mdx