docs: add installation instructions and distribution methods to README

README.md

@@ -1,2 +1,62 @@
 # renderflow
 ✨ Spec-driven document rendering engine (Markdown → PDF/HTML/LaTeX)
+
+## Installation
+
+### Download from GitHub Releases (recommended)
+
+Pre-built binaries are available for Linux, macOS, and Windows on the [Releases page](https://github.com/egohygiene/renderflow/releases).
+
+**Linux:**
+```bash
+curl -L https://github.com/egohygiene/renderflow/releases/latest/download/renderflow-linux -o renderflow
+chmod +x renderflow
+sudo mv renderflow /usr/local/bin/
+```
+
+**macOS:**
+```bash
+curl -L https://github.com/egohygiene/renderflow/releases/latest/download/renderflow-macos -o renderflow
+chmod +x renderflow
+sudo mv renderflow /usr/local/bin/
+```
+
+**Windows:**
+
+Download `renderflow-windows.exe` from the [Releases page](https://github.com/egohygiene/renderflow/releases/latest) and place it somewhere on your `PATH`.
+
+### Build from source (requires [Rust](https://rustup.rs))
+
+```bash
+cargo install --path .
+```
+
+## Usage
+
+```bash
+# Render using the default renderflow.yaml config
+renderflow build
+
+# Render using a custom config file
+renderflow build --config custom.yaml
+
+# Shorthand: pass the config file directly (equivalent to renderflow build --config my-project.yaml)
+renderflow my-project.yaml
+
+# Preview what would be built without creating any files
+renderflow build --dry-run
+```
+
+> **Note:** The argument to `renderflow` is always a YAML configuration file. The Markdown file to render is specified inside the config under the `input` key (e.g. `input: "input.md"`).
+
+### Configuration
+
+Renderflow is driven by a YAML configuration file (default: `renderflow.yaml`):
+
+```yaml
+input: "input.md"
+output_dir: "dist"
+outputs:
+  - type: pdf
+  - type: html
+```