message: Update README.md
  Fix name for the rdkit source directory
diff: @@ -77,7 +77,7 @@ git clone https://github.com/gnina/gnina.git
  cd gnina
  wget https://github.com/rdkit/rdkit/archive/Release_2017_03_1.tar.gz
  tar -xvf Release_2017_03_1.tar.gz
  -cd Release_2017_03_1
  +cd rdkit-Release_2017_03_1
  export RDBASE=`pwd`
  export LD_LIBRARY_PATH=$RDBASE/lib:$LD_LIBRARY_PATH
  mkdir build
  