I am trying to publish my Go package so it is visible on doc search and go search, and can be installed with go get.
However, the one document I found doesn't clearly tell me how to get the documentation generated and hosted, or to publish the package at all. How can I publish my package?
You already did it.
All you must do to "publish" a Go package is make it available via a public URL. By putting it on GitHub, you have already published your package. You can view the GoDoc as proof. It may take time for the doc search to update, but once you've loaded the GoDoc once on your own, the indexing will happen automatically.
As for Go search, just click the Add Packages link at the top of the page.