Fix apikey-secret README.md
Fix apikey-secret README.md

Following the existing README instructions would result in an error
when the user attempted to create the secret.  This small change
remediates the instruction so that the secret is successfully created.

Signed-off-by: rgee0 <320bca71fc381a4a025636043ca86e734e31cf8b@technologee.co.uk>

alexellis/faas,rgee0/faas,alexellis/faas,alexellis/faas,rgee0/faas,rgee0/faas,alexellis/faas,rgee0/faas,openfaas/faas,alexellis/faas,openfaas/faas,rgee0/faas,alexellis/faas,rgee0/faas,alexellis/faas,openfaas/faas,alexellis/faas,rgee0/faas,rgee0/faas,alexellis/faas,rgee0/faas,rgee0/faas