Info-directory-list

Info-directory-list is a variable defined in `info.el'.
Its value is

nil

Documentation:
List of directories to search for Info documentation files.
If nil, meaning not yet initialized, Info uses the environment
variable INFOPATH to initialize it, or `Info-default-directory-list'
if there is no INFOPATH variable in the environment, or the
concatenation of the two if INFOPATH ends with a `path-separator'.

When `Info-directory-list' is initialized from the value of
`Info-default-directory-list', and Emacs is installed in one of the
standard directories, the directory of Info files that come with Emacs
is put last (so that local Info files override standard ones).

When `Info-directory-list' is initialized from the value of
`Info-default-directory-list', and Emacs is not installed in one
of the standard directories, the first element of the resulting
list is the directory where Emacs installs the Info files that
come with it. This is so that Emacs's own manual, which suits the
version of Emacs you are using, will always be found first. This
is useful when you install an experimental version of Emacs without
removing the standard installation.

If you want to override the order of directories in
`Info-default-directory-list', set INFOPATH in the environment.

If you run the Emacs executable from the `src' directory in the Emacs
source tree, and INFOPATH is not defined, the `info' directory in the
source tree is used as the first element of `Info-directory-list', in
place of the installation Info directory. This is useful when you run
a version of Emacs without installing it.