Update release.md to move space limit requirement to the correct place

Signed-off-by: Wenjia Zhang <[email protected]>

Documentation/contributor-guide/release.md

@@ -57,12 +57,11 @@ which don't need to be executed before releasing each version.
 2. Ensure you have a Linux machine, on which the git, Golang, and docker have been installed.
     - Ensure the Golang version matches the version defined in `.go-version` file.
     - Ensure non-privileged users can run docker commands, refer to the [Linux postinstall](https://docs.docker.com/engine/install/linux-postinstall/).
-    - Ensure there is at least 500MB of free space on your Linux machine.
+    - Ensure there is at least 5GB of free space on your Linux machine.
 3. Install gsutil, refer to [gsutil_install](https://cloud.google.com/storage/docs/gsutil_install). When asked about cloud project to use, pick `etcd-development`.
 4. Authenticate the image registry, refer to [Authentication methods](https://cloud.google.com/container-registry/docs/advanced-authentication).
    - `gcloud auth login`
    - `gcloud auth configure-docker`
-5. Ensure there is at least 500MB of free space on your Linux machine.
 
 ### Release steps