adding HindEncorp
@lhoestq I have created a new PR by reforking and creating a new branch  @rahul-art unfortunately this didn't quite work, here's how you can try again:
- `git checkout master` to go back to the main branch
- `git pull upstream master` to make it up to date
- `git checkout -b add_hind_encorp` to create a new branch

Then add the dataset script, `README.md`, `dummy_data.zip`, and `dataset_infos.json` to the tracked files for the branch with `git add` (please add all of these files individually, NOT the whole directory as we don't want the other data files)
Then after you have passed the style checks and the local tests, do:
- `git commit . -m initial_commit`
- `git push --set-upstream origin add_hind_encorp`

Then you can go to this branch on the WebApp and open a new PR @yjernite #1557 created new PR
adding Hindi Wikipedia corpus