Update README.md (#190)

README.md

@@ -66,6 +66,7 @@ usual CMake flags `-DCMAKE_BUILD_TYPE=Debug` or `-DCMAKE_BUILD_TYPE=Release`.
 ```shell
 	mkdir build && cd build
 	cmake -DCMAKE_BUILD_TYPE=Release ..
+	make -j 10
 ```
 
 ## Running
@@ -102,4 +103,4 @@ that the implementation in code can be written exactly the same as the maths on
 paper (i.e. there are no arbitrary normalised units). We avoid Hartree atomic
 units because the scales are quite a bit smaller than the relevant spin dynamic 
 scales and there's a high potential for bugs, for example because moments are
-multiples of $2\mu_B$.
+multiples of $2\mu_B$.