[#5496] docs: update launch Gravitino playground instructions (#5505)

### What changes were proposed in this pull request?

Add instructions for launching the playground with Git and a single curl
command.

### Why are the changes needed?

Provide instructions for users to launch the playground.

Fix: #5496

### Does this PR introduce _any_ user-facing change?

  1. Change in how-to-use-the-playground.md

### How was this patch tested?

Use Markdown Live Preview.
https://markdownlivepreview.com/

docs/how-to-use-the-playground.md

@@ -13,7 +13,7 @@ Depending on your network and computer, startup time may take 3-5 minutes. Once
 
 ## Prerequisites
 
-Install Git, Docker, Docker Compose.
+Install Git (optional), Docker, Docker Compose.
 
 ## System Resource Requirements
 
@@ -36,6 +36,16 @@ The playground runs several services. The TCP ports used may clash with existing
 
 ### Launch playground
 
+You can launch the playground in two ways:
+
+1. Use a single curl command
+
+```shell
+/bin/bash -c "$(curl -fsSL https://raw.githubusercontent.com/apache/gravitino-playground/HEAD/install.sh)"
+```
+
+2. Use Git
+
 ```shell
 git clone [email protected]:apache/gravitino-playground.git
 cd gravitino-playground