Added instructions on how to add chart repository

[JGrzybowski]

It's a small PR with something that might be handy to all the people that come from non-containerized world.

When I first discovered this repo it was hard for me to find where to find the URL of the chart repo. It would be great to be able to find it with search.

I accept the repositories CLA.

[JGrzybowski]

Also, please add hacktoberfest or hacktoberfest-accepted tag if this will get merged.

[JGrzybowski]

@callumpjackson can you add hacktoberfest-accepted label to this PR? I would much appreciate it. It keeps my motivation high to do more for Open Source projects.

[callumpjackson]

done