Exdir file example

[luihabl]

Hi! I am currently developing a code that will use the Exdir format and it would be really useful to have a link in the README to download an example of an .exdir file. If possible, it would be really cool if this sample file was "complex", with datasets, groups and attributes. This would make the life of people who is starting to addopt the format much easier.

[dragly]

Good point! We can provide such an example.