This mechanism for configuring plugins is now deprecated, since it's not
capable of declaring plugin versions. Instead, we recommend just placing
plugins into a particular directory, which is now documented on the
main providers documentation page and linked from the more detailed docs
on plugins in general.
* update plugin/provider to make clear this section isn't needed for regular use
* add some links and notes about getting started
* remove the mention of binaries... I 'm not sure it's needed yet
* 'Installing Terraform Providers' section
* sometimes I can't words good
* move the 'installing providers' block
* cleanup of terms
* copy that update to plugins/provider too