Flesh out README

Author: rdmurphy

README.md

@@ -1,6 +1,6 @@
 # Typebundle
 
-Zero-config Node.js library bundler with support for Babel-transpiled TypeScript. A work in progress!
+Zero-config Node.js library bundler with support for Babel-transpiled TypeScript. A work in progress! Outputs both compiled JavaScript and valid TypeScript `d.ts` files.
 
 ## Installation
 
@@ -11,7 +11,45 @@ npm i -D typebundle
 ## Usage
 
 ```sh
-npx typebundle <input> --output=<output_directory>
+typebundle <input> [--options]
+```
+
+Typebundle's primary interface is on the command line. The only required positional argument is `<input>`, which tells `typebundle` which files to consider entry points. Any glob that's compatible with `tiny-glob` is valid and switches `typebundle` into multi-entry mode if it finds multiple files.
+
+#### A single source file
+
+```sh
+typebundle src/index.ts --output dist --target 8
+```
+
+#### Multiple source files
+
+```sh
+typebundle "src/{cli,index}.ts" --output dist --target 8
+```
+
+#### Run in watch mode
+
+```sh
+typebundle src/index.ts --output dist --target 8 --watch
+```
+
+## Options
+
+```
+--output      The output directory, defaults to "dist"
+
+--compress    If passed, "terser" will be used to minify the output
+
+--target      The minimum version of Node.js to target for transpiling, this
+              is passed directly to "@babel/preset-env" at "targets.node",
+              defaults to "current"
+
+--types       The directory where "d.ts" files are output, defaults to where
+              --output is set
+
+--watch       Watches source files for changes and re-builds, does not output
+              "d.ts" files for speed
 ```
 
 ## License