More reference link on Acknowledgement

[Kin-Zhang]

Thanks for your work.
And I'm wondering about the link on Acknowledgement
VDB Ros Wrapper inside this package is developed by Rohit Garg I didn't find the link on github with Rohit Garg
The ETHZ-ASL work, does that mean the GitHub repo of voxblox or others?

The VDB Ros Wrapper inside this package is developed by Rohit Garg from Air Lab CMU based on the work of ETHZ ASL