Added first description of the model
Added general description, information about the tags and also some example usage code.
# [Codecov](https://codecov.io/gh/huggingface/transformers/pull/5672?src=pr&el=h1) Report
> Merging [#5672](https://codecov.io/gh/huggingface/transformers/pull/5672?src=pr&el=desc) into [master](https://codecov.io/gh/huggingface/transformers/commit/201d23f2854c7a13d3c32df4947af9fd7365c2cd&el=desc) will **decrease** coverage by `0.12%`.
> The diff coverage is `n/a`.

[![Impacted file tree graph](https://codecov.io/gh/huggingface/transformers/pull/5672/graphs/tree.svg?width=650&height=150&src=pr&token=9qOlN6Hb1c)](https://codecov.io/gh/huggingface/transformers/pull/5672?src=pr&el=tree)

```diff
@@            Coverage Diff             @@
##           master    #5672      +/-   ##
==========================================
- Coverage   77.34%   77.22%   -0.13%     
==========================================
  Files         146      146              
  Lines       25948    25948              
==========================================
- Hits        20070    20038      -32     
- Misses       5878     5910      +32     
```


| [Impacted Files](https://codecov.io/gh/huggingface/transformers/pull/5672?src=pr&el=tree) | Coverage Δ | |
|---|---|---|
| [src/transformers/modeling\_tf\_distilbert.py](https://codecov.io/gh/huggingface/transformers/pull/5672/diff?src=pr&el=tree#diff-c3JjL3RyYW5zZm9ybWVycy9tb2RlbGluZ190Zl9kaXN0aWxiZXJ0LnB5) | `64.90% <0.00%> (-33.90%)` | :arrow_down: |
| [src/transformers/generation\_tf\_utils.py](https://codecov.io/gh/huggingface/transformers/pull/5672/diff?src=pr&el=tree#diff-c3JjL3RyYW5zZm9ybWVycy9nZW5lcmF0aW9uX3RmX3V0aWxzLnB5) | `83.95% <0.00%> (-2.51%)` | :arrow_down: |
| [src/transformers/modeling\_tf\_roberta.py](https://codecov.io/gh/huggingface/transformers/pull/5672/diff?src=pr&el=tree#diff-c3JjL3RyYW5zZm9ybWVycy9tb2RlbGluZ190Zl9yb2JlcnRhLnB5) | `93.36% <0.00%> (+49.37%)` | :arrow_up: |

------

[Continue to review full report at Codecov](https://codecov.io/gh/huggingface/transformers/pull/5672?src=pr&el=continue).
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> `Δ = absolute <relative> (impact)`, `ø = not affected`, `? = missing data`
> Powered by [Codecov](https://codecov.io/gh/huggingface/transformers/pull/5672?src=pr&el=footer). Last update [223084e...4c2abf8](https://codecov.io/gh/huggingface/transformers/pull/5672?src=pr&el=lastupdated). Read the [comment docs](https://docs.codecov.io/docs/pull-request-comments).
