Added README.md to Swedish BERT models from National Library of Sweden
Following the lead of others these are not actual model cards but rather the README.md-files from https://github.com/Kungbib/swedish-bert-models
# [Codecov](https://codecov.io/gh/huggingface/transformers/pull/2716?src=pr&el=h1) Report
> Merging [#2716](https://codecov.io/gh/huggingface/transformers/pull/2716?src=pr&el=desc) into [master](https://codecov.io/gh/huggingface/transformers/commit/2ba147ecffa28e5a4f96eebd09dcd642117dedae?src=pr&el=desc) will **not change** coverage.
> The diff coverage is `n/a`.

[![Impacted file tree graph](https://codecov.io/gh/huggingface/transformers/pull/2716/graphs/tree.svg?width=650&token=9qOlN6Hb1c&height=150&src=pr)](https://codecov.io/gh/huggingface/transformers/pull/2716?src=pr&el=tree)

```diff
@@           Coverage Diff           @@
##           master    #2716   +/-   ##
=======================================
  Coverage   74.09%   74.09%           
=======================================
  Files          93       93           
  Lines       15248    15248           
=======================================
  Hits        11298    11298           
  Misses       3950     3950
```



------

[Continue to review full report at Codecov](https://codecov.io/gh/huggingface/transformers/pull/2716?src=pr&el=continue).
> **Legend** - [Click here to learn more](https://docs.codecov.io/docs/codecov-delta)
> `Δ = absolute <relative> (impact)`, `ø = not affected`, `? = missing data`
> Powered by [Codecov](https://codecov.io/gh/huggingface/transformers/pull/2716?src=pr&el=footer). Last update [2ba147e...e46c8bf](https://codecov.io/gh/huggingface/transformers/pull/2716?src=pr&el=lastupdated). Read the [comment docs](https://docs.codecov.io/docs/pull-request-comments).
<|||||>Thanks @marma! 

As also mentioned on https://github.com/huggingface/transformers/pull/2720#issuecomment-581430234, we'll find a way for users to get merge rights on their model cards (via a GitHub bot maybe)
