Update DEVELOPMENT.md with additional build info

Author: michaelmdresser

DEVELOPMENT.md

@@ -1,5 +1,19 @@
 # Development
 
+## Building development images
+
+```sh
+export TDTAG="dockerregistry.example.com/cluster-turndown:X.Y.Z"
+docker build -t "${TDTAG}" .
+docker push "${TDTAG}"
+
+# Then update the image in your cluster
+kubectl set image \
+    -n turndown \
+    deployment/cluster-turndown \
+    cluster-turndown="${TDTAG}"
+```
+
 ## Generating turndown schedule CRD code
 
 To re-generate the code for the defined CRDs, do the following:
@@ -11,8 +25,8 @@ The script is based on https://github.com/kubernetes/sample-controller, specific
 
 ## Cutting a release
 
-1. Call `update-version.sh VERSION`, e.g. `./update-version.sh 1.3.0`
-2. Build and push the new image to GCR (`make release`)
+1. Call `update-version.sh VERSION`, e.g. `./update-version.sh X.Y.Z`
+2. Build and push the new image to GCR (`make VERSION=X.Y.Z release`)
 3. Merge the changes
 4. Tag a new release off of `develop` for the new version
 5. Manually upload `artifacts/cluster-turndown-full.yaml` and `scripts/gke-create-service-key.sh` to the GitHub Release created by the tag