Creates an index for a data collection.
The index can't be used immediately, as the process of generating the index takes time. You can check whether an index is ready by calling List Indexes.
Note that when an index fails to create, the failed index still occupies a slot. To remove the failed index and free up the slot for a new index, call Drop Index.
You can only call this method when authenticated as a Wix app or Wix user identity.