fix: fix duplicate model get help text (#188)

# What does this PR do?
[Provide a short summary of what this PR does and why. Link to relevant
issues if applicable.]

```
from:
$ llama-stack-client models
Usage: llama-stack-client models [OPTIONS] COMMAND [ARGS]...

  Manage GenAI models.

Options:
  --help  Show this message and exit.

Commands:
  get         Show available llama models at distribution endpoint <<<--
  list        Show available llama models at distribution endpoint

to:
$ llama-stack-client models
Usage: llama-stack-client models [OPTIONS] COMMAND [ARGS]...

  Manage GenAI models.

Options:
  --help  Show this message and exit.

Commands:
  get         Show details of a specific model at the distribution endpoint <<<--
  list        Show available llama models at distribution endpoint
```

[//]: # (If resolving an issue, uncomment and update the line below)
[//]: # (Closes #[issue-number])

## Test Plan
[Describe the tests you ran to verify your changes with result
summaries. *Provide clear instructions so the plan can be easily
re-executed.*]

[//]: # (## Documentation)
[//]: # (- [ ] Added a Changelog entry if the change is significant)

Signed-off-by: reidliu41 <reid201711@gmail.com>
Co-authored-by: reidliu41 <reid201711@gmail.com>

Author: reidliu41

src/llama_stack_client/lib/cli/models/models.py

@@ -70,7 +70,7 @@ def list_models(ctx):
 @click.pass_context
 @handle_client_errors("get model details")
 def get_model(ctx, model_id: str):
-    """Show available llama models at distribution endpoint"""
+    """Show details of a specific model at the distribution endpoint"""
     client = ctx.obj["client"]
     console = Console()