Fix section leveling.

[deflaux]

Old:

• http://googlegenomics.readthedocs.org/en/latest/index.html
• http://googlegenomics.readthedocs.org/en/latest/sections/access_data.html

New:

• http://googlegenomics.readthedocs.org/en/staging/index.html
• http://googlegenomics.readthedocs.org/en/staging/sections/access_data.html

[iliat]

LGTM. Thanks !