validation should probably ignore certain files

[Remi-Gau]

I am getting a validation workflow to fail because one of the files in the folder is a markdown file.

https://github.com/ReproNim/reproschema/actions/runs/9053352785/job/24872007262?pr=487

See here: https://github.com/Remi-Gau/reproschema/tree/fix/doc-2/example_ehi/protocols

• This combined with #11 is kind of a maddening combo where things fails and you don't know why or for what files.

My suggestion would be that validation should only be run on files with no extension or a .jsonld extentions.