exbert links for my albert model cards
Adding links for exbert visualization.
Hi @elgeish , you also need to add a 

```
tags:
- exbert
```

to the metadata block.

<|||||># [Codecov](https://codecov.io/gh/huggingface/transformers/pull/3729?src=pr&el=h1) Report
> Merging [#3729](https://codecov.io/gh/huggingface/transformers/pull/3729?src=pr&el=desc) into [master](https://codecov.io/gh/huggingface/transformers/commit/ce2298fb5f84a8d0d8860c15fb677b7ada07a8ad&el=desc) will **increase** coverage by `0.01%`.
> The diff coverage is `n/a`.

[![Impacted file tree graph](https://codecov.io/gh/huggingface/transformers/pull/3729/graphs/tree.svg?width=650&height=150&src=pr&token=9qOlN6Hb1c)](https://codecov.io/gh/huggingface/transformers/pull/3729?src=pr&el=tree)

```diff
@@            Coverage Diff             @@
##           master    #3729      +/-   ##
==========================================
+ Coverage   78.18%   78.20%   +0.01%     
==========================================
  Files         104      104              
  Lines       17799    17799              
==========================================
+ Hits        13917    13919       +2     
+ Misses       3882     3880       -2     
```


| [Impacted Files](https://codecov.io/gh/huggingface/transformers/pull/3729?src=pr&el=tree) | Coverage Δ | |
|---|---|---|
| [src/transformers/modeling\_tf\_utils.py](https://codecov.io/gh/huggingface/transformers/pull/3729/diff?src=pr&el=tree#diff-c3JjL3RyYW5zZm9ybWVycy9tb2RlbGluZ190Zl91dGlscy5weQ==) | `92.96% <0.00%> (+0.16%)` | :arrow_up: |
| [src/transformers/modeling\_transfo\_xl.py](https://codecov.io/gh/huggingface/transformers/pull/3729/diff?src=pr&el=tree#diff-c3JjL3RyYW5zZm9ybWVycy9tb2RlbGluZ190cmFuc2ZvX3hsLnB5) | `77.22% <0.00%> (+0.21%)` | :arrow_up: |

------

[Continue to review full report at Codecov](https://codecov.io/gh/huggingface/transformers/pull/3729?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/3729?src=pr&el=footer). Last update [ce2298f...e003d19](https://codecov.io/gh/huggingface/transformers/pull/3729?src=pr&el=lastupdated). Read the [comment docs](https://docs.codecov.io/docs/pull-request-comments).
<|||||>Thanks!