Add ENTRYPOINT_PROCESS to docker documentation

docs/docker/run.md

@@ -58,3 +58,4 @@
     2) all guild tools env variable can be used to start a new container using custom values by using the "-e" option.
     3) CPU and RAM and Shared Memory allocation option for the container can be used when you start the container (i.e. --shm-size or --memory or --cpus [official docker resource docs](https://docs.docker.com/config/containers/resource_constraints/))
     4) `--env MITHRIL_DOWNLOAD=Y` # This option will allow Mithril client to download the latest Mithril snapshot of the blockchain when the container starts and does not have a copy of the blockchain yet. This is useful when you want to start a new node from scratch and don't want to wait for the node to sync from the network. This option is only available for the mainnet, preprod, and preview networks.
+    5) `--env ENTRYPOINT_PROCESS=mithril-signer.sh` # This option will allow the container to start the Mithril signer process instead of the node process. This is useful when you want to run a Mithril signer node and have the container setup the configuration files based on the NETWORK environment varaible.