fix(reallife/tutorial): cockpit integration for plugins

describe simplest possible way to add the plugin

related to #CAM-2560
chore(migration guide): add section about upgrade over multiple patch versions

related to #CAM-2485
chore(connector): add REST connector example to docs

related to #CAM-2564
fix(user guide): proof read and correct connector section

related to #CAM-2564
fix(user guide): proof read and correct variable serialization

related to #CAM-2433
chore(enterprise): update download 7.2.0-alpha4
chore(caseExecution): expose activityId and activityName

related to CAM-2536
chore(caseExecution): expose parentId
chore(migration): add patch script instructions

refer to #CAM-2567
chore(case/status): adjust docs about returned status codes

related to CAM-2404
impr(userguide/scripting): add hint about Groovy & Javascript
chore(rest): add 403 return codes

related to #CAM-2404
impr(reference/bpmn): remove misleading sentence
chore(bpmn/REST): expose caseInstanceId

related to CAM-2510
chore(user-guide): fix code highlighting in spring and cdi section
chore(task/REST): provide docs how to create or update a task

related to CAM-2374, CAM-2619
feat(user-guide): document expression language

related to #CAM-1065
chore(enterprise): update download 7.1.5
chore(userguide/el): improve section on built-in variables

related to #CAM-1065
chore(procDef/REST): expose caseInstanceid

related to CAM-2370