Improved docstring.
Improved docstring.

Added note about units.

git-svn-id: 38f1702c2d2bc28f7341d40983eddaad0d99b903@114 37378900-1858-4726-a06b-e54562fdc990

chatelak/RMG-Py,nyee/RMG-Py,nyee/RMG-Py,KEHANG/RMG-Py,pierrelb/RMG-Py,enochd/RMG-Py,comocheng/RMG-Py,chatelak/RMG-Py,enochd/RMG-Py,nickvandewiele/RMG-Py,nickvandewiele/RMG-Py,pierrelb/RMG-Py,faribas/RMG-Py,faribas/RMG-Py,KEHANG/RMG-Py,comocheng/RMG-Py