OptionRomPkg/ReadMe.txt: Remove VS2005
    
    Remove VS2005 in Build Validation.
    https://bugzilla.tianocore.org/show_bug.cgi?id=1377
    
    Cc: Ray Ni <ray.ni@intel.com>
    Contributed-under: TianoCore Contribution Agreement 1.1
    Signed-off-by: Shenglei Zhang <shenglei.zhang@intel.com>
    Reviewed-by: Liming Gao <liming.gao@intel.com>