GitLab

Correct documentation so all commands should be run from the root
of the git directory.

Also clarifies usage on label maps. In a nutshell, label map IDs
should start at index 1 (and not include 0).

from Google internal link

Fix URL

Thanks for the good work!

For details see our paper:
"Speed/accuracy trade-offs for modern convolutional object detectors."
Huang J, Rathod V, Sun C, Zhu M, Korattikara A, Fathi A, Fischer I,
Wojna Z, Song Y, Guadarrama S, Murphy K, CVPR 2017
https://arxiv.org/abs/1611.10012