Add SciTLDR Dataset (Take 2)
@lhoestq please review this PR when you get free If the CI fails just because of `RemoteDatasetTest` errors it's fine, they're fixed on master > If the CI fails just because of `RemoteDatasetTest` errors it's fine, they're fixed on master

The same 3 tests are failing again :(
```
FAILED tests/test_dataset_common.py::RemoteDatasetTest::test_builder_class_norwegian_ner
FAILED tests/test_dataset_common.py::RemoteDatasetTest::test_builder_configs_norwegian_ner
FAILED tests/test_dataset_common.py::RemoteDatasetTest::test_load_dataset_norwegian_ner
``` One trick if you want to add more datasets to avoid these errors : you can just rebase the master branch of your fork from the master branch of the repo. Then each time you make a new branch from master on your fork, it will include the fix for these errors > One trick if you want to add more datasets to avoid these errors : you can just rebase the master branch of your fork from the master branch of the repo. Then each time you make a new branch from master on your fork, it will include the fix for these errors

Yes, I almost always do that, but somehow seems even this branch got old 😓 
I also do the following if I directly create a new branch locally: `git checkout -b <branchname> upstream/master` so it stays up-to date irrespective of my fork, still don't know how this crept in again Merging this one since the CI is fixed on master
Adds the SciTLDR Dataset by AI2
Added the `README.md` card with tags to the best of my knowledge

Multi-target summaries or TLDRs of Scientific Documents

Continued from #986 