[docs] add htop to monitor docker behavior during CI build       sphinx 1.8 (default version on ubuntu) breaks documentation build. Fix this
[docs] add htop to monitor docker behavior during CI build
      sphinx 1.8 (default version on ubuntu) breaks documentation build. Fix this

siconos/siconos,fperignon/siconos,radarsat1/siconos,fperignon/siconos,fperignon/siconos,radarsat1/siconos,fperignon/siconos,siconos/siconos,radarsat1/siconos,siconos/siconos,radarsat1/siconos,fperignon/siconos,siconos/siconos,radarsat1/siconos