fix: Fix links in sample READMEs

contributing/samples/hello_world/README.md

@@ -0,0 +1,41 @@
+# Hello World Sample Agent
+
+This sample demonstrates a basic agent in the Agent Development Kit (ADK) that can roll dice and check if numbers are prime.
+
+## Overview
+
+The Hello World sample consists of a single agent that can perform two main tasks:
+- Rolling a die with a specified number of sides.
+- Checking if a list of numbers contains any prime numbers.
+
+## Key Features
+
+- **`roll_die(sides: int)`**: A tool that simulates rolling a die. It takes the number of sides as input and returns the result.
+- **`check_prime(nums: list[int])`**: A tool that checks for prime numbers in a given list of integers.
+
+## Usage
+
+To run this agent, use the `adk web` command from the root of the repository:
+
+```bash
+adk web contributing/samples/
+```
+
+Then, navigate to the web interface and select the "hello_world" agent.
+
+## Example Interactions
+
+**Rolling a die:**
+```
+User: Roll a 20-sided die
+```
+
+**Checking for prime numbers:**
+```
+User: Is 13 a prime number?
+```
+
+**Combined operation:**
+```
+User: Roll a 10-sided die and tell me if the result is a prime number.
+```

contributing/samples/multi_agent_llm_config/README.md

@@ -1,3 +1,3 @@
 # Config-based Agent Sample - LLM multi-agent
 
-http://google3/third_party/py/google/adk/open_source_workspace/contributing/samples/hello_world_ma/
+This sample is based on the [Hello World Multi-Agent sample](../hello_world_ma/).

contributing/samples/tool_human_in_the_loop_config/README.md

@@ -1,3 +1,3 @@
 # Config-based Agent Sample - Human-In-The-Loop
 
-http://google3/third_party/py/google/adk/open_source_workspace/contributing/samples/human_in_loop/
+This sample is based on the [Human-In-The-Loop sample](../human_in_loop/).