SDL_ttf: Add instructions for downloading external dependencies

From 51860cd270bf8068c7e0f5ddd0929b0c794b12d6 Mon Sep 17 00:00:00 2001
From: Sam Lantinga <[EMAIL REDACTED]>
Date: Thu, 20 Feb 2025 15:29:39 -0800
Subject: [PATCH] Add instructions for downloading external dependencies

---
 docs/INTRO-emscripten.md   | 2 ++
 docs/INTRO-visualstudio.md | 2 ++
 docs/INTRO-xcode.md        | 2 ++
 3 files changed, 6 insertions(+)

diff --git a/docs/INTRO-emscripten.md b/docs/INTRO-emscripten.md
index 1bfaa9d0..ad1a60ee 100644
--- a/docs/INTRO-emscripten.md
+++ b/docs/INTRO-emscripten.md
@@ -9,6 +9,8 @@ First, you should have the Emscripten SDK installed from:
 
 https://emscripten.org/docs/getting_started/downloads.html
 
+Now make sure you have downloaded the external dependencies. You can do that by running `download.sh` in the external directory.
+
 Create the file CMakeLists.txt
 ```cmake
 cmake_minimum_required(VERSION 3.16)
diff --git a/docs/INTRO-visualstudio.md b/docs/INTRO-visualstudio.md
index d1b80380..acb4cfb1 100644
--- a/docs/INTRO-visualstudio.md
+++ b/docs/INTRO-visualstudio.md
@@ -3,6 +3,8 @@
 
 The easiest way to use SDL_ttf is to include it along with SDL as subprojects in your project.
 
+First, make sure you have downloaded the external dependencies. You can do that by running `Get-GitModules.ps1` in the external directory.
+
 We'll start by creating a simple project to build and run [hello.c](hello.c)
 
 - Create a new project in Visual Studio, using the C++ Empty Project template
diff --git a/docs/INTRO-xcode.md b/docs/INTRO-xcode.md
index 0e4af2bb..4c9cd468 100644
--- a/docs/INTRO-xcode.md
+++ b/docs/INTRO-xcode.md
@@ -3,6 +3,8 @@
 
 The easiest way to use SDL_ttf is to include it along with SDL as subprojects in your project.
 
+First, make sure you have downloaded the external dependencies. You can do that by running `download.sh` in the external directory.
+
 We'll start by creating a simple project to build and run [hello.c](hello.c)
 
 - Create a new project in Xcode, using the App template and selecting Objective C as the language