What this PR does / why we need it:
As of the latest CAPO docs it's possible to leave the external network ID empty if there is only a one external network which will be picked automatically.
Which issue(s) this PR fixes(optional, in fixes #<issue number>(, fixes #<issue_number>, ...) format, will close the issue(s) when PR gets merged):
Fixes #100
What this PR does / why we need it: As of the latest CAPO docs it's possible to leave the external network ID empty if there is only a one external network which will be picked automatically.
Which issue(s) this PR fixes (optional, in
fixes #<issue number>(, fixes #<issue_number>, ...)format, will close the issue(s) when PR gets merged): Fixes #100