fix: derive DEEPOPS_VERSION for script debug output

scripts/common.sh printed an always-empty DEEPOPS_VERSION unless a user
happened to set it in config/env.sh. Default it to the checkout's git tag
description (git describe --tags --always) with an unknown fallback, keep
the env.sh override, and document the variable in config.example/env.sh.

Author: dholt

config.example/env.sh

@@ -4,3 +4,7 @@
 # See deepops/scripts/common.sh for implementation details
 
 DEEPOPS_EXAMPLE_VAR=""
+
+# DeepOps version reported in script debug output.
+# Defaults to the checkout's git tag description; uncomment to override.
+# DEEPOPS_VERSION=""

scripts/common.sh

@@ -19,5 +19,11 @@ else
   source ${DEEPOPS_CONFIG_DIR}/env.sh
 fi
 
+# Determine the DeepOps version for debug output.
+# Can be overridden in config/env.sh; defaults to the checkout's git tag description.
+if [ -z "${DEEPOPS_VERSION}" ]; then
+  DEEPOPS_VERSION="$(git -C "${ROOT_DIR}" describe --tags --always 2>/dev/null || echo unknown)"
+fi
+
 # Print out base debug
 echo "Starting '${0}';  DeepOps version '${DEEPOPS_VERSION}'"