Add custom volume for configuration files

Add custom directory volume to Docker build

Author: wukongdaily

.github/workflows/build-iso-25.12.x.yml

@@ -77,6 +77,7 @@ jobs:
               -v "${{ github.workspace }}/bin:/home/build/immortalwrt/bin" \
               -v "${{ github.workspace }}/files:/home/build/immortalwrt/files" \
               -v "${{ github.workspace }}/x86-64/imm.config:/home/build/immortalwrt/.config" \
+              -v "${{ github.workspace }}/custom:/home/build/immortalwrt/files/etc/config" \
               -v "${{ github.workspace }}/shell:/home/build/immortalwrt/shell" \
               -v "${{ github.workspace }}/x86-64/build25.sh:/home/build/immortalwrt/build.sh" \
               -e PROFILE=$profile \