A bit more explanation of what is what in metadata list

git-svn-id: https://chaste.cs.ox.ac.uk/svn/chaste/trunk@21316 b5f69653-2bf5-0310-8201-b0dafb8e1405
#2300 Small increment to testing process (preparation for direct flux solver).

git-svn-id: https://chaste.cs.ox.ac.uk/svn/chaste/trunk@21318 b5f69653-2bf5-0310-8201-b0dafb8e1405