Add brief notes on Golang module creation

golang/creating-new-golang-module.md

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+I was using go version 1.22.4 while writing these notes.  I do not
+know whether recommendations have changed across go versions.
+
+It seems to be recommended to have one module per revision-controlled
+repository, e.g. per Github repository.
+
+There should be a single `go.mod` and `go.sum` file in the root
+directory of the repository.
+
+Such a repository can have many separate programs, each with their own
+main package, preferably in different directories of the repo.
+
+To create the initial `go.mod` file for the repository, after Go is
+installed on the system so you can run `go` commands, change to the
+root directory of the repository and run this command:
+
+```bash
+go mod init wwwin-github.cisco.com/jafinger/misc
+```
+
+Replace the URL with the URL of your repository.  Omit any `https://`
+or `http://` prefix, and any `.git` suffix.