Add some text in the cmakelist in order to inform the user that turning...

Add some text in the cmakelist in order to inform the user that turning sse-avx to on is mainly used in the P2P

CMakeLists.txt

@@ -61,8 +61,8 @@ if (MORSE_DISTRIB_DIR OR EXISTS "${CMAKE_SOURCE_DIR}/CMakeModules/morse/")
   option( ScalFMM_USE_DOUBLE_PRECISION "Set to ON to compile in double precision"    ON  )
   option( ScalFMM_ATTACHE_SOURCE       "Set to ON to compile with -g"                OFF )
   option( ScalFMM_USE_ADDONS           "Set to ON to compile add ons"                OFF )
-  option( ScalFMM_USE_SSE              "Set to ON to compile with SSE support"       ON  )
-  option( ScalFMM_USE_AVX              "Set to ON to compile with AVX support"       OFF  )
+  option( ScalFMM_USE_SSE              "Set to ON to compile with SSE support (and use intrinsec SSE P2P)"       ON  )
+  option( ScalFMM_USE_AVX              "Set to ON to compile with AVX support (and use intrinsec AVX P2P)"       OFF  )
   option( ScalFMM_USE_ASSERT           "Set to ON to enable safe tests during execution" ON  )
   option( ScalFMM_USE_MIC_NATIVE       "Set to ON to compile in native mode for MIC" OFF  )
   option( ScalFMM_BUILD_ONLY_LIB       "Set to ON to compile only the lib (examples are not compiled) " OFF  )