Clean up whitespace in README
Clean up whitespace in README

Un-indent the opening brace of the controller IAM policy. Use two spaces
per indent in the node IAM policy, as it is in the controller policy.
Clean up some trailing whitespaces. Do not use trailing empty lines in
code blocks, do add them before the next heading.

Signed-off-by: Matthias Rampke <e388d34fd3c0456122779e95f262c0d70198a168@rampke.de>

kubernetes/cloud-provider-aws,kubernetes/cloud-provider-aws,kubernetes/cloud-provider-aws