Disable netgo for dynbinary builds

It's not necessary to use the netgo implementation for non-static builds. :)

Docker-DCO-1.1-Signed-off-by: Andrew Page <admwiggin@gmail.com> (github: tianon)
Fix minor typo and improve wording
Clean up some uses on 'an' in builder docs
Merge pull request #6553 from tianon/disable-netgo-for-dynbinary

Disable netgo for dynbinary builds
Merge pull request #6578 from ch3pjw/documentation_fix

Fix minor typo and improve wording