Rewrite README with install, config, and usage examples

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

README.md

@@ -1,28 +1,50 @@
-# csc : Cluster SSH Command
+# csc — Cluster SSH Command
 
-Launch command over SSH on cluster hosts with "dialog" DEBIAN_FRONTEND.
+Run a command over SSH on a group of hosts, with colored per-host output and progress tracking.
 
-## Tree
+## Install
+
+Copy `csc` somewhere in your `$PATH` and make it executable:
 
 ```bash
-$ tree
-.
-├── csc
-└── README.md
+cp csc ~/.local/bin/csc
+chmod +x ~/.local/bin/csc
+```
 
-0 directories, 2 files
+## Configuration
+
+Host groups are plain text files under `~/.config/csc/` (one hostname per line, `#` comments supported):
+
+```
+# ~/.config/csc/webservers
+web01.example.com
+web02.example.com
+# web03.example.com  (disabled)
 ```
 
 ## Usage
 
-```bash
-$ csc -h
+```
 Usage: csc [OPTION]... [COMMAND]
   -h  show help
   -v  enable verbose mode
-  -c  specify config dir, default is /home/flo/.config/csc
+  -c  specify config dir, default is ~/.config/csc
   -g  specify group
   -d  enable dry run mode
 ```
 
-Host group file must exists under config dir, one host per line.
+```bash
+csc -g webservers uptime
+csc -g webservers -d "apt-get upgrade -y"   # dry run: shows commands, no ssh
+csc -g webservers -v df -h                  # verbose
+csc -g webservers -c /etc/csc uptime        # custom config dir
+```
+
+## Output
+
+```
+[1/2] "uptime" on web01  →  ssh -t web01 "TERM=xterm DEBIAN_FRONTEND=dialog uptime"
+✓ ok
+[2/2] "uptime" on web02  →  ...
+✗ failed (exit 255)
+```