correcting book cover image name

git-svn-id: svn+ssh://svn.code.sf.net/p/pcgen/code/Trunk@21895 ef53c05b-3124-4d59-ae7d-fe3273f42be7
shortening names

git-svn-id: svn+ssh://svn.code.sf.net/p/pcgen/code/Trunk@21896 ef53c05b-3124-4d59-ae7d-fe3273f42be7