Fix an example of env command (#7603)

# Description

Fix an example of `env` command

# 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` to check that you're using the standard code
style
- `cargo test --workspace` to check that all tests pass

# 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/env/env_command.rs

@@ -77,7 +77,7 @@ impl Command for Env {
             },
             Example {
                 description: "Check whether the env variable `MY_ENV_ABC` exists",
-                example: r#"env | any name == MY_ENV_ABC"#,
+                example: r#"env | any { |e| $e.name == MY_ENV_ABC }"#,
                 result: Some(Value::test_bool(false)),
             },
             Example {