docs: clarify target option, closes egoist#769

docs/README.md

@@ -290,7 +290,26 @@ Code splitting currently only works with the `esm` output format, and it's enabl
 
 To disable code splitting altogether, try the `--no-splitting` flag instead.
 
-### ES5 support
+### Target environment
+
+You can use the `target` option in `tsup.config.ts` or the `--target` flag to set the target environment for the generated JavaScript and/or CSS code. Each target environment is an environment name followed by a version number. The following environment names are currently supported:
+
+- chrome
+- edge
+- firefox
+- hermes
+- ie
+- ios
+- node
+- opera
+- rhino
+- safari
+
+In addition, you can also specify JavaScript language versions such as `es2020`.
+
+The value for `target` defaults to `compilerOptions.target` in your `tsconfig.json`, or `node14` if unspecified. For more information check out esbuild's [target](https://esbuild.github.io/api/#target) option.
+
+#### ES5 support
 
 You can use `--target es5` to compile the code down to es5, in this target your code will be transpiled by esbuild to es2020 first, and then transpiled to es5 by [SWC](https://swc.rs).
 

package.json

@@ -63,7 +63,7 @@
     "svelte": "3.46.4",
     "ts-essentials": "9.1.2",
     "tsconfig-paths": "3.12.0",
-    "tsup": "6.0.1",
+    "tsup": "6.4.0",
     "typescript": "4.6.3",
     "vitest": "0.21.1",
     "wait-for-expect": "3.0.2"