cherrypick: Remove unnecessary LICENSE-docs (#2636)

## Summary:

Cherry pick
facebook@ef7f714
, so we can merge this separately from #2620 and not block the CI there.

```
Summary:
Pull Request resolved: facebook#48670

The `LICENSE-docs` was needed when this repo was also containing the reactnative.dev docs. As this is not the case anymore, this file is unncessary.

Changelog:
[Internal] [Changed] - Remove unnecessary LICENSE-docs

Reviewed By: cipolleschi

Differential Revision: D68156336

fbshipit-source-id: 489bf2cb95916c20eb61bfb00e34b8e271bc08e3
```

Co-authored-by: Nicola Corti <[email protected]>

Author: Saadnajmi