Show how to add third-party PyPI dependencies

Add an "Adding Dependencies" section to README and a guiding
comment in pyproject.toml's dependencies list.

Author: wu-vincent

README.md

@@ -55,6 +55,18 @@ src/endstone_example/
   config.toml       Default config (copied on first run)
 ```
 
+## Adding Dependencies
+
+To use third-party packages from PyPI, add them to the `dependencies` list in `pyproject.toml`:
+
+```toml
+[project]
+dependencies = ["requests>=2.31", "aiosqlite>=0.19"]
+```
+
+Then run `uv sync` (or `pip install -e .`) to install them. They will be bundled automatically
+when you build the wheel.
+
 ## Install on a Server
 
 ```bash

pyproject.toml

@@ -5,7 +5,7 @@ build-backend = "hatchling.build"
 [project]
 name = "endstone-example"
 dynamic = ["version"]
-dependencies = []
+dependencies = []  # Add third-party PyPI packages here, e.g. ["requests>=2.31"]
 authors = [
     { name = "Endstone Developers", email = "hello@endstone.dev" },
 ]