fix(bpmn references): proofread and correct

related to #CAM-2375

Conflicts:
	site/src/documents/api-references/bpmn20/10-tasks/40-script-task.html.md
	site/src/documents/api-references/bpmn20/30-events/10-start-events.html.md
	site/src/documents/api-references/bpmn20/30-events/30-message-events.html.md
	site/src/documents/api-references/bpmn20/30-events/50-error-events.html.md
	site/src/documents/api-references/bpmn20/30-events/70-cancel-and-compensation-events.html.md
	site/src/documents/api-references/bpmn20/30-events/80-link-events.html.md
	site/src/documents/api-references/bpmn20/40-subprocesses/30-event-subprocess.html.md
	site/src/documents/api-references/bpmn20/50-custom-extensions/10-camunda-elements.html.md
	site/src/documents/api-references/bpmn20/50-custom-extensions/20-camunda-attributes.html.md