Update vendoring documentation for go modules

docs/development/vendoring.md

@@ -15,28 +15,26 @@ update commands:
 * [go mod](https://github.com/golang/go/wiki/Modules) for kops 1.15 and newer branches (including master)
 * [hg](https://www.mercurial-scm.org/wiki/Download)
 
-<!-- TODO: update dependency management for go mod -->
-
 ## Adding a dependency to the vendor directory
 
-The `dep` tool will manage required dependencies based on the imports
+Go modules will manage required dependencies based on the imports
 found in the source code. Follow these steps to run the update process:
 
 1. Add the desired import to a `.go` file.
-1. Run `make dep-ensure` to start the update process. If this step is
+2. Run `make gomod` to start the update process. If this step is
 successful, the imported dependency will be added to the `vendor`
 subdirectory.
 1. Commit any changes, including changes to the `vendor` directory,
-`Gopkg.lock` and `Gopkg.toml`.
+`go.mod`, and `go.sum`.
 1. Open a pull request with these changes separately from other work
 so that it is easier to review.
 
 ## Updating a dependency in the vendor directory (e.g. aws-sdk-go)
 
-1. Update the locked version as specified in Gopkg.toml
-1. Run `make dep-ensure`.
-1. Review the changes to ensure that they are as intended / trustworthy.
-1. Commit any changes, including changes to the `vendor` directory,
-`Gopkg.lock` and `Gopkg.toml`.
+1. Update the locked version as specified in `go.mod`
+2. Run `make gomod`.
+3. Review the changes to ensure that they are as intended / trustworthy.
+4. Commit any changes, including changes to the `vendor` directory,
+`go.mod` and `go.sum`.
 1. Open a pull request with these changes separately from other work so that it
 is easier to review.  Please include any significant changes you observed.