Update go dependencies

vendor/cloud.google.com/go/RELEASING.md

@@ -1,13 +1,47 @@
-# How to Release this Repo
+# How to Create a New Release
 
-1. Determine the current release version with `git tag -l`. It should look
-   something like `vX.Y.Z`. We'll call the current
-   version `$CV` and the new version `$NV`.
-1. On master, run `git log $CV..` to list all the changes since the last
-   release.
-1. Edit  `CHANGES.md` to include a summary of the changes.
-1. Mail the CL containing the `CHANGES.md` changes. When the CL is approved, submit it.
-1. Without submitting any other CLs:
-   a. Switch to master.
-   b. Tag the repo with the next version: `git tag $NV`.
-   c. Push the tag: `git push origin $NV`.
+## Prerequisites
+
+Install [releasetool](https://github.com/googleapis/releasetool).
+
+## Create a release
+
+1. `cd` into the root directory, e.g., `~/go/src/cloud.google.com/go`
+1. Checkout the master branch and ensure a clean and up-to-date state.
+    ```
+    git checkout master
+    git pull --tags origin master
+    ```
+1. Run releasetool to generate a changelog from the last version. Note,
+   releasetool will prompt if the new version is a major, minor, or patch
+   version.
+    ```
+    releasetool start --language go
+    ```
+1. Format the output to match CHANGES.md.
+1. Submit a CL with the changes in CHANGES.md. The commit message should look
+   like this (where `v0.31.0` is instead the correct version number):
+    ```
+    all: Release v0.31.0
+    ```
+1. Wait for approval from all reviewers and then submit the CL.
+1. Return to the master branch and pull the release commit.
+    ```
+    git checkout master
+    git pull origin master
+    ```
+1. Tag the current commit with the new version (e.g., `v0.31.0`)
+    ```
+    releasetool tag --language go
+    ```
+1. Publish the tag to GoogleSource (i.e., origin):
+    ```
+    git push origin $NEW_VERSION
+    ```
+1. Visit the [releases page][releases] on GitHub and click the "Draft a new
+   release" button. For tag version, enter the tag published in the previous
+   step. For the release title, use the version (e.g., `v0.31.0`). For the
+   description, copy the changes added to CHANGES.md.
+
+
+[releases]: https://github.com/GoogleCloudPlatform/google-cloud-go/releases