[ci skip] add installation note/fix for macos 15

Author: pmocz

docs/source/installation.rst

@@ -115,6 +115,11 @@ uses export to set variables):
     # add shmesa (the MESA command line tool) to your PATH 
     export PATH=$PATH:$MESA_DIR/scripts/shmesa
 
+Note (Jan 2025): due to some changes in MacOS 15.2/15.3, if you see the error `ld: library 'z' not found` on a Mac you may also need to add:
+
+.. code-block:: bash
+
+    export SDKROOT=$(xcrun --sdk macosx --show-sdk-path)
 
 If your machine uses csh as its shell, use ``setenv`` instead of ``export``.