feat: files.list replaces hardcoded array when non-empty

Previously files.list appended to the built-in DOTFILES array, causing
duplicate processing. Now a non-empty files.list replaces the array
entirely; missing or empty file falls back to the hardcoded defaults.

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

1 files changed, 9 insertions, 6 deletions

diff --git a/README.md b/README.md
index 1a5f0ed..d75e366 100644
--- a/README.md
+++ b/README.md
@@ -135,15 +135,18 @@ GIT_BRANCH="master"
 
 ## Adding Files
 
-**Edit the script** — add paths to the `DOTFILES` array in `dot-backup.sh`.
-
-**Or use the external list** — add paths to `~/.config/dot-backup/files.list`, one per line:
+**External list (recommended)** — create `~/.config/dot-backup/files.list` with one path per line. When this file exists and is non-empty it replaces the built-in list entirely:
 
 ```
-# extra dotfiles
-.config/myapp
-.config/otherapp.conf
+# shell
+.bashrc
+.bash_aliases
+
+# system files
 /etc/hosts
+/etc/fstab
 ```
 
+**Built-in fallback** — if `files.list` is missing or empty, the script uses the `DOTFILES` array hardcoded in `dot-backup.sh`.
+
 Relative paths are treated as `$HOME`-relative. Absolute paths (starting with `/`) are treated as system files.