Update link to Tute sample queries.

[deflaux]

To be merged after https://github.com/googlegenomics/bigquery-examples/pull/39

Preview here:

• http://googlegenomics.readthedocs.io/en/staging/use_cases/annotate_variants/tute_annotation.html
• http://googlegenomics.readthedocs.io/en/staging/use_cases/discover_public_data/tute_genomics_public_data.html

Change-Id: I5e9d1c0858f83fb2722d8e26a65feb17d8f08f83

[deflaux]

PTAL, thanks!