doc: explain why passing -mlinker-version is required
doc: explain why passing -mlinker-version is required

Former-commit-id: 388b4253e31448f209a6265817ac99015e4864f0
syscoin/syscoin,syscoin/syscoin,syscoin/syscoin,syscoin/syscoin,syscoin/syscoin,syscoin/syscoin,syscoin/syscoin,syscoin/syscoin