feat(REST): add documentation for follow-up date of task

related to #CAM-1654
fix(examplelinks): adjust links to new structure of example repo
feat(rest/businessKey): Add docu to use the businessKey

- it is possible to set the business key when start a process instance
or submit a start task form

related to #CAM-1123
fix(reallife/jsf): link to example
improve(docpad) enable syntax highlighting

 * add highlight callback to the marked plugin
 * use github styling of highlight.js

Closes #CAM-1692
fix(doc) some typos and update copyright
feat(engine-rest): Extend documentation to get process definition by key

- process definition by key returns the latest version
- given process definition by key allows all operations like
process definition by id

related to #CAM-1505
chore(get/procDef): Adjust example url to get a process definition

related to CAM-1505
chore(rest-api/procDef): Improve docu to get a process definition by key

related to #CAM-1505
improve(enterprise): add latest download links

add download links for camunda-bpmn-7.0.5
feat(wls-engine-rest): document engine-rest usage on wls

related to CAM-1677
feat(wls-camunda-webapp): document camunda-webapp install on wls

related to CAM-1678
fix(migration-guide): fix remove section tags

Releated to #cam-1695
feat(single-page): Add everything to single page documentation
feat(wls-engine-rest): document engine-rest usage on wls

related to CAM-1677
feat(wls-camunda-webapp): document camunda-webapp install on wls

related to CAM-1678
fix(install-guide): layout improvements and modeler tile
doc(install-guide): review WebLogic parts

related to #CAM-1677 and #CAM-1678
chore(supported-environments): update supp envs.

related to CAM-1683
improve(migration-guide): Add patch level upgrade

related to #CAM-1720

- remove chapter Migrate your Process Application