Document requirement to use --build flag

[CrowdHailer]

Before tagging/pushing an image need to make sure the image is built to the latest version.
This error can cause confusion because of the volume mounting and live reloading.

The only technical solution is to rely on CI to build from source instead of pushing images.
This note should form the start of a Troubleshooting section.

The question tag is "Is there any better solution than just remembering the build step"?