Documentation: Add ImageMagick as dependency for macOS

Author: gmta

Documentation/BuildInstructionsMacOS.md

@@ -8,7 +8,7 @@ Make sure you also have all the following dependencies installed:
 
 ```console
 # core
-brew install coreutils e2fsprogs qemu bash gcc@10 ninja cmake ccache rsync
+brew install coreutils e2fsprogs qemu bash gcc@10 imagemagick ninja cmake ccache rsync
 
 # (option 1) fuse + ext2
 brew install m4 autoconf automake libtool