[docs] Update aspire do --list-steps docs to require step argument

src/frontend/src/content/docs/reference/cli/commands/aspire-do.mdx

@@ -96,15 +96,15 @@ The following options are available:
 
 Before executing a pipeline step, you can discover what steps are available in your application's pipeline and understand their dependencies. Aspire provides two complementary tools for this:
 
-- `aspire do --list-steps` — a quick, compact listing of every pipeline step with its direct dependencies and tags. Available on `aspire deploy`, `aspire publish`, `aspire destroy`, and `aspire do`. Useful for a fast "what would happen?" view before running a command.
+- `--list-steps` — a quick, compact listing of the steps the selected pipeline command would inspect or execute, with each step's direct dependencies and tags. Use it as `aspire deploy --list-steps`, `aspire publish --list-steps`, `aspire destroy --list-steps`, or `aspire do <step> --list-steps`; the `aspire do` form always requires the target `<step>`. Useful for a fast "what would happen?" view before running a command.
 - `aspire do diagnostics` — a verbose, in-depth report. The `diagnostics` step is itself part of the pipeline, so `aspire do diagnostics` runs it like any other step.
 
 ### Quick listing with `--list-steps`
 
-Running `aspire do --list-steps` produces a numbered list of every step in the pipeline, what each one depends on, and any tags it carries:
+The `--list-steps` option requires a `step` argument when used with `aspire do`. Pass the name of the step you want to inspect — for example `deploy` or `publish` — to list the target step and its transitive dependencies, along with each step's direct dependencies and tags. In typical pipelines, listing from `deploy` covers the deployment graph; listing from a leaf step shows only that step.
 
 ```bash title="Aspire CLI"
-aspire do --list-steps
+aspire do deploy --list-steps
 ```
 
 Example output:
@@ -165,10 +165,10 @@ The following examples demonstrate common pipeline operations:
 - Quickly list the steps in your pipeline:
 
   ```bash title="Aspire CLI"
-  aspire do --list-steps
+  aspire do deploy --list-steps
   ```
 
-  This displays a compact view of every step with its dependencies and tags. Use it for a fast "what would happen?" check before running a pipeline command.
+  Pass any well-known step name (such as `deploy` or `publish`) to display a compact view of that step and its transitive dependencies, with each step's direct dependencies and tags. The `step` argument is required; omitting it returns a friendly error that suggests the correct form. Use this for a fast "what would happen?" check before running a pipeline command.
 
 - Run the `diagnostics` step for an in-depth report: