Missing step for "Add existing kubernetes cluster documentation"

Problem to solve

Details: As a new developer I wanted to add existing kubernetes cluster to local gdk environment and followed the guide. Running kubectl … command after completing all previous steps returned: The connection to the server localhost:8080 was refused - did you specify the right host or port?. So as discussed in "kubernetes" channel some info about prerequisites to installation is missing in the docs and needs to be added.

This issue as a follow up of this slack thread about connecting kubernetes cluster to local gdk.

Who can address the issue

@eread

Other links/references

https://gitlab.slack.com/archives/C3UCHUA76/p1564585519041000