Update README.md

README.md

 Basics
 ======
 
-Download last hysop version :
-
-code::
+Download last hysop version:
 
     git clone git@gitlab.com:LJK/hysop.git
 
-build::
+build
 
     mkdir build
-	    cd build
-		    cmake path-to-hysop
-			    make
-				    make install
+	cd build
+    cmake path-to-hysop
+	make -j N
+	make install
 
+N number of available mpi processes.
 
-run in python interactive session::
+run in python interactive session:
 
     import hysop
 
-or using command-line::
+or using command-line:
 
     mpirun -np 4 python yourfile.py