Small bug in a documentation

[AcckiyGerman]

Tasks

• fix docs

Analysis

There is a example about unpivot feature:

unpivot:
    -
      name: ([0-9]{4}) (\\w+)  # regex for original column
      keys:
        year: \\1  # First member of group from above
        direction: \\2  # Second member of group from above

I'm not sure why is here double backslash \\1 in the readme, but when I use dpp in a pipeline processor with this example I got ERROR :Failed to cast row: Field "year" can't cast value "\1" for type "year" with format "default". With \1 everything is ok.

Please, somebody ping me to ensure that there is no special reasons to use double backslash \\ and I'll fix the doc.