* plugin/header: run go gen and small doc updates

Run go gen to enable the new plugin, this should fix the CI failures.
Small tweaks to the docs.
Signed-off-by: Miek Gieben <miek@miek.nl>

* another typo
Signed-off-by: Miek Gieben <miek@miek.nl>

* gofmt
Signed-off-by: Miek Gieben <miek@miek.nl>