Remove unnecessary LICENSE-docs (facebook#48670)

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

Author: cortinico