VPN-7269 update documentation (#10782)

Author: mcleinman

docs/Building/ios.md

@@ -32,6 +32,20 @@ $ ./scripts/macos/conda_setup_qt.sh
 
 Complete the steps in [macOS.md#configure-xcode-build-environment](./macos.md#configure-xcode-build-environment).
 
+## Create symbolic links for iOS SDKs
+**(Only for macOS 26 and higher.)**
+
+_Xcode 26 has changed where iOS SDKs are stored. Symbolic links must be created so `qt-cmake` can find the SDK.
+(If a future version of `qt-cmake` changes how it looks for iOS SDKs, this section can be removed.)
+
+```bash
+$ cd /Applications/Xcode.app/Contents/Developer/Platforms/iPhoneOS.platform/Developer/SDKs/
+$ ln -s iPhoneOS.sdk iPhoneOS18.1.sdk # (for iOS 18.1 - change the version number for other SDK versions)
+```
+
+*Important: The specific iOS SDK versions must also be downloaded via Xcode. Creating a symbolic link will not download the SDK automatically.*
+
+
 ## Build
 
 Configure, using the qt-cmake

docs/Building/macos.md

@@ -114,26 +114,6 @@ This will produce an macOS installer package at `build-macos/macos/pkg/MozillaVP
 
 # Building with Xcode
 
-## Configure Xcode build environment
-
-You need to tell Xcode where to find the versions of rust and go that we have installed in our
-conda environment.
-
-First find and go to the Xcode `/usr/bin` directory. The `xcrun` step you ran earlier will give you a hint
-where to look. It is usually, `/Applications/Xcode.app/Contents/Developer/usr/bin/`.
-
-```
-cd /Applications/Xcode.app/Contents/Developer/usr/bin/
-```
-
-Now activate your conda environment
-
-```
-conda activate vpn
-```
-
-# Building
-
 Use the same configure command above and use `-GXcode` as the CMake generator:
 
 ```