Don't recreate old docs
Change the check to look at a directory on the doc hosts instead of CircleCI to avoid creating old docs at each commit.
# [Codecov](https://codecov.io/gh/huggingface/transformers/pull/5243?src=pr&el=h1) Report
> Merging [#5243](https://codecov.io/gh/huggingface/transformers/pull/5243?src=pr&el=desc) into [master](https://codecov.io/gh/huggingface/transformers/commit/173528e3685bc4321630b7f979d01896c57a5c15&el=desc) will **increase** coverage by `0.02%`.
> The diff coverage is `n/a`.

[![Impacted file tree graph](https://codecov.io/gh/huggingface/transformers/pull/5243/graphs/tree.svg?width=650&height=150&src=pr&token=9qOlN6Hb1c)](https://codecov.io/gh/huggingface/transformers/pull/5243?src=pr&el=tree)

```diff
@@            Coverage Diff             @@
##           master    #5243      +/-   ##
==========================================
+ Coverage   77.96%   77.99%   +0.02%     
==========================================
  Files         138      138              
  Lines       23839    23839              
==========================================
+ Hits        18586    18593       +7     
+ Misses       5253     5246       -7     
```


| [Impacted Files](https://codecov.io/gh/huggingface/transformers/pull/5243?src=pr&el=tree) | Coverage Δ | |
|---|---|---|
| [src/transformers/modeling\_utils.py](https://codecov.io/gh/huggingface/transformers/pull/5243/diff?src=pr&el=tree#diff-c3JjL3RyYW5zZm9ybWVycy9tb2RlbGluZ191dGlscy5weQ==) | `91.26% <0.00%> (+0.12%)` | :arrow_up: |
| [src/transformers/modeling\_tf\_utils.py](https://codecov.io/gh/huggingface/transformers/pull/5243/diff?src=pr&el=tree#diff-c3JjL3RyYW5zZm9ybWVycy9tb2RlbGluZ190Zl91dGlscy5weQ==) | `86.15% <0.00%> (+0.29%)` | :arrow_up: |
| [src/transformers/modeling\_openai.py](https://codecov.io/gh/huggingface/transformers/pull/5243/diff?src=pr&el=tree#diff-c3JjL3RyYW5zZm9ybWVycy9tb2RlbGluZ19vcGVuYWkucHk=) | `80.90% <0.00%> (+1.38%)` | :arrow_up: |

------

[Continue to review full report at Codecov](https://codecov.io/gh/huggingface/transformers/pull/5243?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/5243?src=pr&el=footer). Last update [173528e...80b87e8](https://codecov.io/gh/huggingface/transformers/pull/5243?src=pr&el=lastupdated). Read the [comment docs](https://docs.codecov.io/docs/pull-request-comments).
