Gonna try asking here because the bot didnt understand me. What if I have a folder about a lake and in that folder is seperate text files about the lake itself and its history. It also contains folders for the 5 towns the lake encompasses. In each folder are text files with information about the communities in that town. What kind of index would I use to make sure llamma chain understands the heiarchy. I was told I could DirectoryReader class and add Field_Names that would be embedded with the file to give it context. Just not sure which type of index to use