ci-build: Improve build-deploy script (#19653)

Signed-off-by: Arve Knudsen <arve.knudsen@gmail.com>

scripts/build/ci-build/README.md

@@ -18,3 +18,6 @@ This is a container for cross-platform builds of Grafana. You can run it locally
 * `make attach`
   - Opens bash within the running container
 
+## Build/Publish Docker Image
+In order to build and publish the Grafana build Docker image, execute the following:
+`./build-deploy.sh`.

scripts/build/ci-build/build-deploy.sh

 #!/bin/bash
+set -eo pipefail
 
 _version="1.2.9"
 _tag="grafana/build-container:${_version}"
 
+_dpath=$(dirname "${BASH_SOURCE[0]}")
+cd "$_dpath"
+
 docker build -t $_tag .
 docker push $_tag