feat: runCommand to support interactive write+read

Author: AriPerkkio

README.md

@@ -111,14 +111,33 @@ await webcontainer.mount({
 
 ##### `runCommand`
 
-Run command inside webcontainer. Returns command output.
+Run command inside webcontainer.
 
 ```ts
 await webcontainer.runCommand("npm", ["install"]);
+```
+
+Calling `await` on the result resolves into the command output:
 
+```ts
 const files = await webcontainer.runCommand("ls", ["-l"]);
 ```
 
+To write into the output stream, use `write` method of the non-awaited output.
+
+To verify output of continuous stream, use `waitForText()`:
+
+```ts
+const { write, waitForText, isDone } = webcontainer.runCommand("npm", [
+  "create",
+  "vite",
+]);
+
+await waitForText("What would you like to call your project?");
+await write("Example Project");
+await isDone;
+```
+
 ##### `readFile`
 
 WebContainer's [`readFile`](https://webcontainers.io/guides/working-with-the-file-system#readfile) method.