Update macOS building instructions

.github/workflows/apple.yml

@@ -151,7 +151,7 @@ jobs:
           HOMEBREW_NO_AUTO_UPDATE=1 brew install dylibbundler
           lipo -create ./macosx-x86_64/supertuxkart.app/Contents/MacOS/supertuxkart ./macosx-arm64/supertuxkart.app/Contents/MacOS/supertuxkart -output ./macosx-arm64/supertuxkart.app/Contents/MacOS/supertuxkart
           chmod 755 ./macosx-arm64/supertuxkart.app/Contents/MacOS/supertuxkart
-          dylibbundler -od -b -x ./macosx-arm64/supertuxkart.app/Contents/MacOS/supertuxkart -d ./macosx-arm64/supertuxkart.app/Contents/libs/ -p @executable_path/../libs/ -s dependencies-macosx/lib
+          dylibbundler -od -b -x ./macosx-arm64/supertuxkart.app/Contents/MacOS/supertuxkart -d ./macosx-arm64/supertuxkart.app/Contents/libs/ -p @executable_path/../libs/ -s dependencies-macosx/lib -ns
           # We use SDL_Vulkan_LoadLibrary for 10.9 compatibility, so otool -L supertuxkart has no libMoltenVK.dylib
           cp ./dependencies-macosx/lib/libMoltenVK.dylib ./macosx-arm64/supertuxkart.app/Contents/libs/
           cd ./macosx-arm64/supertuxkart.app/Contents/Resources/data

INSTALL.md

@@ -253,7 +253,9 @@ Add ` -DCMAKE_OSX_DEPLOYMENT_TARGET=10.9` for 10.9 compatibility.
 By default, the executable that is produced is not ready for distribution. Install <https://github.com/auriamg/macdylibbundler> and run:
 
 ```bash
-dylibbundler -od -b -x ./bin/SuperTuxKart.app/Contents/MacOS/supertuxkart -d ./bin/SuperTuxKart.app/Contents/libs/ -p @executable_path/../libs/
+dylibbundler -od -b -x ./bin/SuperTuxKart.app/Contents/MacOS/supertuxkart -d ./bin/SuperTuxKart.app/Contents/libs/ -p @executable_path/../libs/ -s ../dependencies-macosx/lib
 ```
 
+Add `-ns` to disable ad-hoc codesigning
+
 Afterwards, copy the contents of `stk-assets` into `/SuperTuxKart.app/Contents/Resources/data`.