fix nblink to include image of pachyderm example

[RafalSkolasinski]

What this PR does / why we need it:
Minor doc fix that makes sure that image renders properly in Pachyderm example.

[RafalSkolasinski]

/approve

[seldondev]

[APPROVALNOTIFIER] This PR is APPROVED

This pull-request has been approved by: RafalSkolasinski

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[seldondev]

Thu Jan 7 14:12:06 UTC 2021
The logs for [pr-build] [1] will show after the pipeline context has finished.
https://github.com/SeldonIO/seldon-core/blob/gh-pages/jenkins-x/logs/SeldonIO/seldon-core/PR-2820/1.log

impatient try
jx get build logs SeldonIO/seldon-core/PR-2820 --build=1

[seldondev]

Thu Jan 7 14:12:13 UTC 2021
The logs for [lint] [2] will show after the pipeline context has finished.
https://github.com/SeldonIO/seldon-core/blob/gh-pages/jenkins-x/logs/SeldonIO/seldon-core/PR-2820/2.log

impatient try
jx get build logs SeldonIO/seldon-core/PR-2820 --build=2