migrate to hantim org and consolidate deploy secret name

- Update all references from timothykim/ to hantim/ org
- Rename DEPLOY_KEY to DEPLOY_SSH_KEY everywhere
- Update README to reference org-level secrets

setup.sh

@@ -7,7 +7,7 @@ set -euo pipefail
 #
 # Usage:
 #   1. dnf install -y git
-#   2. git clone https://git.timothykim.net/timothykim/hantim-server.git /opt/hantim
+#   2. git clone https://git.timothykim.net/hantim/hantim-server.git /opt/hantim
 #   3. bash /opt/hantim/setup.sh
 #
 
@@ -22,7 +22,7 @@ fi
 
 if [ "$(dirname "$(readlink -f "$0")")" != "$REPO_DIR" ]; then
     echo "ERROR: Repo does not appear to be cloned to $REPO_DIR."
-    echo "  git clone https://git.timothykim.net/timothykim/hantim-server.git $REPO_DIR"
+    echo "  git clone https://git.timothykim.net/hantim/hantim-server.git $REPO_DIR"
     exit 1
 fi