hawkBit rest docs (management & DDI API) (#688)

* hawkBit REST docs.

Signed-off-by: kaizimmerm <kai.zimmermann@bosch-si.com>

* Fiy gitignore.

Signed-off-by: kaizimmerm <kai.zimmermann@bosch-si.com>

* Add to website.

Signed-off-by: kaizimmerm <kai.zimmermann@bosch-si.com>

* Switch to generated docs.

Signed-off-by: kaizimmerm <kai.zimmermann@bosch-si.com>

* Fix typos.

Signed-off-by: kaizimmerm <kai.zimmermann@bosch-si.com>

* Review findings.

Signed-off-by: kaizimmerm <kai.zimmermann@bosch-si.com>

* Otimizations.

Signed-off-by: kaizimmerm <kai.zimmermann@bosch-si.com>

* Revert accidental checkin.

Signed-off-by: kaizimmerm <kai.zimmermann@bosch-si.com>

* Add security link.

docs/src/main/resources/documentation/interfaces/managementapi/tenant.md

@@ -0,0 +1,6 @@
+---
+layout: documentation
+title: Management-API
+---
+
+<iframe src="../../rest-api/tenant-api-guide.html"></iframe>