Document new install and upgrade options

[VicDeo]

occ upgrade and occ market:upgrade got new option --major

• adjust automated update:
  • when doing minor update of core, don't fetch major version updates of app from marketplace
  • when doing major update of core, fetch major version updates of app from marketplace
• admin must have a way to force major update of app
  • occ upgrade --major
  • occ market update --major
• web UI shows both minor and major update, default on minor

More implementation details are available here
owncloud/market#387 (comment)

[mmattel]

Already done for occ upgrade

docs/modules/administration_manual/pages/configuration/server/occ_command.adoc

Line 3027 in ee289f7

| `--major` | Automatically update apps to new major versions during minor updates of ownCloud Server.

But nobody told that this is also true for occ market:upgrade or I missed that one.
Needs docs update