Plugins documentation is missing all UI elements

[Nikita Koshikov]

Our page https://wiki.openstack.org/wiki/Fuel/Plugins#Plugin_elements_in_the_Fuel_web_UI doesn't mention anything about
    type: "textarea" UI available field and also new 'generators' are coming.

We need to update page to reflect current possible values.

[Bug Checker Bot (esikachev-l)]

(This check performed automatically)
Please, make sure that bug description contains the following sections filled in with the appropriate data related to the bug you are describing:

actual result

version

expected result

steps to reproduce

For more detailed information on the contents of each of the listed sections see https://wiki.openstack.org/wiki/Fuel/How_to_contribute#Here_is_how_you_file_a_bug

[Evgeny Konstantinov (evkonstantinov)]

This was fixed previously. http://docs.openstack.org/developer/fuel-docs/userdocs/fuel-user-guide/maintain-environment/custom-graph.html

feel free to reopen if you think this needs to be changed/improved.