part of EASY-1099

When applied it will

• add some fetch-able files to the resources, such that they exist in the master branch of the project. These will be referenced in the next PR, where an example of a bag with holes will be added. These files contain a couple of distinct properties, such as mime-type, emptiness and (plain) text.
• add the PULL_REQUEST_TEMPLATE.md file. Since this is a new project, this was not yet done.

Where should the reviewer @DANS-KNAW/easy start?

Have fun looking at the files.

How should this be manually tested?

Not at all!