Finish the documentation

README.md

@@ -17,16 +17,41 @@ npm install --save-dev using-temporary-files
 ```js copy
 import { usingTemporaryFiles } from "using-temporary-files";
 
-await usingTemporaryFiles(async ({ path, add, addDirectory, remove }) => {
+await usingTemporaryFiles(async ({ path, add, addDirectory, read, remove }) => {
   path("."); // full path to the temporary directory
   path("file.txt"); // full path to a particular file
-  await add("file.txt", "content"); // add a file
-  const text = await read("file.txt" /*, encoding (optional) */); // read the contents of a file
-  await addDirectory("dir"); // add a directory
+  path("a", "b", "c"); // path segments are joined, e.g. "<tmpdir>/a/b/c"
+  await add("file.txt", "content"); // add a file (creates parent directories as needed)
+  const text = await read("file.txt"); // read the contents of a file (encoding defaults to "utf8")
+  const binary = await read("file.bin", "base64"); // read with a specific encoding
+  await addDirectory("dir"); // add a directory (creates parent directories as needed)
   await remove("file.txt"); // remove a file
 });
 ```
 
+### Multiple callbacks
+
+`usingTemporaryFiles()` accepts any number of callbacks. They share the same temporary directory and are called in order.
+
+```js copy
+await usingTemporaryFiles(
+  async ({ add }) => {
+    await add("file.txt", "Hello, world!");
+  },
+  async ({ read }) => {
+    console.log(await read("file.txt")); // "Hello, world!"
+  }
+);
+```
+
+### Debug mode
+
+Set the environment variable `USING_TEMPORARY_FILES_DEBUG=1` to keep the temporary directory in the current working directory instead of deleting it. This is useful when you need to inspect the files after a test run.
+
+```sh copy
+USING_TEMPORARY_FILES_DEBUG=1 npm test
+```
+
 ## Background
 
 This code was extracted from [Counterfact](https://github.com/pmcelhaney/counterfact) so that it can be