Add GITLAB_SHELL_CUSTOM_HOOKS_DIR

Author: taomaree

assets/runtime/env-defaults

@@ -495,6 +495,9 @@ GITALY_TOKEN=${GITALY_TOKEN:-}
 GITALY_SOCKET_PATH=${GITLAB_INSTALL_DIR}/tmp/sockets/private/gitaly.socket
 GITALY_ADDRESS=${GITALY_ADDRESS:-unix:$GITALY_SOCKET_PATH}
 
+## GitLab Shell
+GITLAB_SHELL_CUSTOM_HOOKS_DIR=${GITLAB_SHELL_CUSTOM_HOOKS_DIR:-"$GITLAB_SHELL_INSTALL_DIR/hooks"}
+
 ## MONITORING
 GITLAB_MONITORING_UNICORN_SAMPLER_INTERVAL=${GITLAB_MONITORING_UNICORN_SAMPLER_INTERVAL:-10}
 GITLAB_MONITORING_IP_WHITELIST=${GITLAB_MONITORING_IP_WHITELIST:-"0.0.0.0/8"}