Clarify example links in README.md.
Clarify example links in README.md.

seung-lab/neuroglancer,seung-lab/neuroglancer,seung-lab/neuroglancer,google/neuroglancer,seung-lab/neuroglancer,google/neuroglancer,seung-lab/neuroglancer,google/neuroglancer,funkey/neuroglancer,janelia-flyem/neuroglancer,janelia-flyem/neuroglancer,google/neuroglancer,janelia-flyem/neuroglancer,janelia-flyem/neuroglancer,funkey/neuroglancer,google/neuroglancer,google/neuroglancer,janelia-flyem/neuroglancer,seung-lab/neuroglancer,funkey/neuroglancer,google/neuroglancer,funkey/neuroglancer,seung-lab/neuroglancer,google/neuroglancer