Documentation: opensource-mods.md: add "Earth Special Forces". #2575

Job	Run time
flatpak (su.xash.Engine.Compat.i386)	3m 51s
build (ubuntu-20.04, linux, amd64)	3m 0s
build (ubuntu-20.04, linux, i386)	3m 26s
build (ubuntu-20.04, linux, arm64, true)	4m 29s
build (ubuntu-20.04, linux, armhf, true)	3m 37s
build (ubuntu-20.04, linux, riscv64, true)	3m 24s
build (ubuntu-20.04, linux, ppc64el, true)	3m 49s
build (ubuntu-20.04, android, multiarch)	10m 52s
build (ubuntu-latest, nswitch, arm64)	3m 20s
build (ubuntu-latest, psvita, armv7hf)	8m 10s
build (windows-latest, win32, amd64)	2m 14s
build (windows-2019, win32, i386)	2m 2s
build (macos-14, apple, arm64)	1m 38s
build (macos-13, apple, amd64)	2m 30s
Upload releases	0s
	56m 22s

Provide feedback