EXCEL - merge files with Powerquery

Powerquery HOW TO merge excel files

http://www.excelguru.ca/blog/2015/02/25/combine-multiple-excel-workbooks-in-power-query/

Advanced editor:
(filepath)=>
let
    Source = Excel.Workbook(File.Contents(filepath), null, true),
    Inventory_Sheet = Source{0}[Data],
    #"Promoted Headers" = Table.PromoteHeaders(Inventory_Sheet)
in
    #"Promoted Headers"

Rename:
fnGetContents

Folder:
M:\Resolution Accuen\Publishers\_Programmatic\Pubdocs

Add Custom Column:
fnGetContents([Folder Path]&[Name])