[dev] feat: README.md (#47)

feat: README.md

README.md

@@ -1 +1,58 @@
 # dotfiles
+
+My personal shell environment and command-line tools, mainly for Linux and
+NixOS systems.
+
+It includes configurations for zsh, tmux, Vim, Git, and SSH, together with a
+few utility scripts used across my machines.
+
+## Highlights
+
+- `riot`: an SSH wrapper with host presets, jump hosts, port forwarding, tmux
+  sessions, and optional GPG agent forwarding.
+- `sagt`: an SSH/GPG agent manager with support for PIV, 1Password, and
+  OpenPGP smart cards.
+- zsh aliases and completions for the bundled tools.
+- tmux and Vim configurations with plugin setup.
+- automatic updates with selectable `main`, `dev`, and `latest` channels.
+
+## Installation
+
+Quick install:
+
+```sh
+curl -fsSL https://dotfiles.cn | bash
+```
+
+Alternatively, clone the repository so the installer can be reviewed first:
+
+```sh
+git clone https://github.com/DictXiong/dotfiles.git ~/dotfiles
+~/dotfiles/install.sh -a
+```
+
+The installer adds small source/include entries to the existing zsh, tmux,
+Vim, and Git configuration files instead of replacing them entirely.
+
+## Useful commands
+
+```sh
+riot --help                 # show the SSH wrapper manual
+sagt                        # start or reuse an ssh-agent
+sagt gpg                    # use gpg-agent as SSH agent
+sagt gpg-pin                # cache the smart-card signature PIN
+dfs update                  # update dotfiles from the selected channel
+dfs config                  # edit machine-specific settings
+```
+
+## Configuration
+
+Machine-specific settings can be placed in:
+
+```text
+~/.config/dotfiles/env
+~/.config/riot-config.sh
+```
+
+This is a personal dotfiles repository. Review the configuration, SSH keys,
+and installation script before using it on another machine.