add_sofc_materials_articles
Hey @lhoestq , thanks for the feedback on this! I updated the `_generate_examples` with some comments on the process, and reduced the `dummy_data.zip` down quite a bit as well. 

For the dummy data, I reduced the text to only three sentences, and aligned the corresponding entity/token/sentence annotations to that (reduced accordingly). The frames file is a strange combined format for the annotations and I found if I reduced that that would break the parser no matter what I did, so I left that as is. The difference between a reduced frames and non-reduced frames file in the compressed dummy data was only about ~4kb, so hopefully leaving this as is will be ok!
adding [SOFC-Exp Corpus](https://arxiv.org/abs/2006.03039)