fix is-admin example (#9350)

# Description

closes #9348 

# User-Facing Changes
<!-- List of all changes that impact the user experience here. This
helps us keep track of breaking changes. -->

# Tests + Formatting
<!--
Don't forget to add tests that cover your changes.

Make sure you've run and fixed any issues with these commands:

- `cargo fmt --all -- --check` to check standard code formatting (`cargo
fmt --all` applies these changes)
- `cargo clippy --workspace -- -D warnings -D clippy::unwrap_used -A
clippy::needless_collect -A clippy::result_large_err` to check that
you're using the standard code style
- `cargo test --workspace` to check that all tests pass
- `cargo run -- crates/nu-std/tests/run.nu` to run the tests for the
standard library

> **Note**
> from `nushell` you can also use the `toolkit` as follows
> ```bash
> use toolkit.nu # or use an `env_change` hook to activate it
automatically
> toolkit check pr
> ```
-->

# After Submitting
<!-- If your PR had any user-facing changes, update [the
documentation](https://github.com/nushell/nushell.github.io) after the
PR is merged, if necessary. This will help us keep the docs up to date.
-->

crates/nu-command/src/experimental/is_admin.rs

@@ -42,7 +42,7 @@ impl Command for IsAdmin {
         vec![
             Example {
                 description: "Return 'iamroot' if nushell is running with admin/root privileges, and 'iamnotroot' if not.",
-                example: r#"if is-admin { "iamroot" } else { "iamnotroot" }"#,
+                example: r#"if (is-admin) { "iamroot" } else { "iamnotroot" }"#,
                 result: Some(Value::test_string("iamnotroot")),
             },
         ]