docs: getting started guide error about max length of name and dry-run

### Description

New to agentcore, found 2 issues on getting started guide:

## name's max length (36 -> 23)

The docs that include wrong information:
https://docs.aws.amazon.com/bedrock-agentcore/latest/devguide/runtime-get-started-cli.html

> --name – The project name (alphanumeric, starts with a letter, max 36 characters).

Error occured when I gave it a name `LangGraphOpenAiNoMemoryNoTool`, it's not long (29 chars) but not allowed

```sh
agentcore create \
--name LangGraphOpenAiNoMemoryNoTool \
--framework LangChain_LangGraph \
--model-provider OpenAI \
--memory none \
--build CodeZip

Project name must be 23 characters or less
```

## unknown option '--plan'

> agentcore deploy --plan

```sh
agentcore deploy --plan
error: unknown option '--plan'
```

### Steps to Reproduce

1. Open https://docs.aws.amazon.com/bedrock-agentcore/latest/devguide/runtime-get-started-cli.html
2. Follow the guidance to create a new project

### Expected Behavior

1. Should allow 36 characters or update doc.
2. Should allow --plan or update doc.

### Actual Behavior

wrong doc

### CLI Version

_No response_

### Operating System

macOS

### Additional Context

_No response_