dired-local-variables-file

dired-local-variables-file is a variable defined in `dired-x.el'.
Its value is

".dired"

• This variable is obsolete since 24.1;
  use `dir-locals-file' instead.

Documentation:
Filename, as string, containing local Dired buffer variables to be hacked.
If this file found in current directory, then it will be inserted into dired
buffer and `hack-local-variables' will be run. See Info node
`(emacs)File Variables' for more information on local variables.
See also `dired-enable-local-variables'.

You can customize this variable.