Custom date format on PowerBI - date

Question

I'm assembling data tables in PowerBI, whose rows and columns are date type, with the format that the program offers, I have managed to change the format to 'January 2018', but I want to visualize 'jan-2018', and that format is not included in the program, what should I do to get a date format like this?
I can't find any answer about my problem on any website.
The code I found is this:
= Table.TransformColumnTypes(#"Promoted Headers",{{"Segmento Cliente", type text}, {"Paquete", type text}, {"Fecha cosecha", type date}, {"Fecha proyectada", type date}, {"Valor", Int64.Type}})
I don't know what to do to change the format.
Help me please, thanks.
EDIT: I tried this, but i get a type text column, and what I want is a type date. Any idea?
Right click your table on the right side, add new column, write code (in data or report view, not in query):
Custom Date = FORMAT('TABLE NAME'[TABLE COLUMN]; "FORMAT")
In your case the format will be MMM - YYYY
To add upper/lower case, put UPPER or LOWER before the FORMAT
Example all uppercase:
Custom Date = UPPER(FORMAT('TABLE NAME'[TABLE COLUMN]; "FORMAT"))

Answer 1

Right click your table on the right side, add new column, write code (in data or report view, not in query):
Custom Date = FORMAT('TABLE NAME'[TABLE COLUMN]; "FORMAT")
In your case the format will be MMM - YYYY
To add upper/lower case, put UPPER or LOWER before the FORMAT
Example all uppercase:
Custom Date = UPPER(FORMAT('TABLE NAME'[TABLE COLUMN]; "FORMAT"))