Update site.rst

Added Braunschweig to site-repos in the wild

Just corrected a typo

Delete builds.rst

This chapter is no longer needed (duplicate content).
The content is alrady in http://gluon.readthedocs.org/en/latest/user/getting_started.html#getting-started .

Update getting_started.rst

Updating OpenWrt accidentally enabled this option.

This chapter is no longer needed (duplicate content).
The content is alrady in http://gluon.readthedocs.org/en/latest/user/getting_started.html#getting-started .

add information about the environment variables.

This significantly improves fastd performance, to the level it was before
Barrier Breaker.

fix typo

the command autoupdate not work, so a fix smal fix necessary