multiple working directory mode, "config" file is shared while
"config.worktree" is per-working directory (i.e., it's in
GIT_COMMON_DIR/worktrees/<id>/config.worktree)
+
+==== `refStorage`
+
+Specifies the file format for the ref database. The only valid value
+is `files` (loose references with a packed-refs file).