Change marker EXCLUDE_ALL to EXCLUDE_FROM_ALL in opm_compile_satellite

Previously, when passing EXCLUDE_ALL to opm_compile_satellite this
resulted a cmake error:

CMake Error at cmake/Modules/UseDebugSymbols.cmake:71 (get_target_property):
  Cannot find source file:

    EXCLUDE_ALL

  Tried extensions .c .C .c++ .cc .cpp .cxx .m .M .mm .h .hh .h++ .hm .hpp
  .hxx .in .txx
Call Stack (most recent call first):
  cmake/Modules/OpmSatellites.cmake:77 (strip_debug_symbols)
  CMakeLists.txt:176 (opm_compile_satellites)
Adjusts macro documentation to recent change.
Merge pull request #57 from blattms/satellite-exclude-all

Change marker EXCLUDE_ALL to EXCLUDE_FROM_ALL in opm_compile_satellite