docs: update README and comments on files.list

Signed-off-by: Camber Huang <camber@poi.science>

Author: CamberLoid

README.md

@@ -1,4 +1,50 @@
 # misc-files
-Repository for miscellaneous files frequently overwritten by upstreams
 
 [![Periodic updates](https://github.com/AOSC-Dev/misc-files/actions/workflows/periodic-update.yml/badge.svg)](https://github.com/AOSC-Dev/misc-files/actions/workflows/periodic-update.yml)
+
+Repository for miscellaneous files frequently overwritten by upstreams.
+
+This repository is driven by the tracking list file `files.list` and utilizes GitHub Actions to keep files updated. Files in this repository are being used by the following packages:
+
+- `iana-etc`: 
+- `bind`
+
+## `files.list`
+
+This file tells what file should be tracked by which package and renamed in the following format:
+
+```
+package-name url [file-name]
+```
+
+Example:
+
+```
+bind https://www.internic.net/zones/named.root
+```
+
+* package-name: The name of the package to which the file belongs
+* url: The URL to download the file from
+* file-name: Optional, will default to `$(basename $url)` if not provided
+
+## How the workflow works?
+
+The main workflow `periodic-update` is triggered under the following conditions:
+
+- Update `files.list` on branch `master`
+- Cron `"0 0 * * *"`
+- Manually triggered by maintainers
+
+When triggered, the workflow:
+
+1. Parses `files.list` to determine which files to download.
+2. Downloads and optionally renames each file, and calculates their checksums.
+3. If changes are detected:
+   - Commits the updates directly to the `master` branch
+   - Then syncs the updated files to their package-specific branch (e.g. `iana-etc`)
+   - Tags the commit in that branch with the current date (e.g. `iana-etc-20250914`)
+4. If no changes are detected, the commit step is skipped and the workflow exits without further action.
+
+## License
+
+The workflow itself is licensed under the MIT License. All other files originated from external sources are subject to their respective upstream license.

files.list

@@ -1,3 +1,6 @@
+# package-name url [file-name]
+# bind https://www.internic.net/zones/named.root
+# iana-etc https://www.iana.org/assignments/service-names-port-numbers/service-names-port-numbers.xml service-names-port-numbers.iana
 bind https://www.internic.net/zones/named.root
 
 iana-etc https://www.iana.org/assignments/service-names-port-numbers/service-names-port-numbers.xml