fix load line

Docker.md

@@ -31,6 +31,33 @@ There is an i2P image available over at [DockerHub](https://hub.docker.com).  If
 docker build -t geti2p/i2p .
 ```
 
+Normally, docker images will be generated using container images that match the architecture of the host system.
+In order to "Cross-Build" a Docker container for a different architecture on the same OS, use:
+```
+docker buildx build --platform=linux/arm64 -t geti2p/i2p-arm64 .
+```
+
+The previous command will build an image which is suitable for Linux environments running on arm64 architectures.
+For example, the Raspberry Pi.
+If you build your image on the host system, i.e. the Raspberry Pi, docker buildx is not required there.
+
+It is necessary to test these images without uploading them to a registry.
+In order to do that, use the `docker save/load` commands.
+In order to move these images between the amd64 build host and the arm64 runtime host, use `docker save` to produce an archive of the image:
+
+```
+docker save --output geti2p.i2p.arm64.tar 'geti2p/i2p-arm64'
+```
+
+And transfer the `geti2p.i2p.arm64.tar` file from the build host to the runtime host, such as with a flash drive or SSH. Then, use `docker load` to load the image from the archive:
+
+```
+docker load --input geti2p.i2p.arm64.tar
+```
+
+These arm64 image builds must be manually pushed to DockerHub by an admin with access to `geti2p/i2p` on DockerHub at release time.
+They **do not** become available automatically.
+
 ### Running a container
 
 #### Environment Variables