docs: Update UI text.

Created by: serenashe

Signed-off-by: serenashe serenashe@kubesphere.io

What type of PR is this?

/kind documentation

What this PR does / why we need it:

Correct an inconsistent name of a parameter in the Create Storage Class dialog box. In the Create Storage Class dialog box, the name of the parameter is Storage System. But on the storage class list page, the name of exactly the same parameter is Provisioner. I consulted @stoneshi-yunify and we concluded that these two parameters should have a consistent name Provisioner.

Special notes for reviewers:

None

Does this PR introduced a user-facing change?

None

/assign @harrisonliu5 Please take a look and help merge this PR. Thx.