directory: update docs to clarify it doesn't really set AUTO_NAME_DIRS (sorin-ionescu#1740)

Module `directory` used to set AUTO_NAME_DIRS. This was changed in
73e94b8 but README.md hasn't been updated. This looks like an
accidental omission that this commit fixes.

Author: romkatv

modules/directory/README.md

@@ -12,7 +12,6 @@ Options
   - `PUSHD_SILENT` does not print the directory stack after `pushd` or `popd`.
   - `PUSHD_TO_HOME` pushes to the home directory when no argument is given.
   - `CDABLE_VARS` changes directory to a path stored in a variable.
-  - `AUTO_NAME_DIRS` auto adds variable-stored paths to `~` list.
   - `MULTIOS` writes to multiple descriptors.
   - `EXTENDED_GLOB` uses extended globbing syntax.
   - `CLOBBER` does not overwrite existing files with `>` and `>>`. Use `>!` and