use/document data directory

releng/run_all_releng

@@ -3,8 +3,9 @@
 set -e
 
 SELF=$(basename "$0")
-CLOG1=log.$SELF.1
-CLOG2=log.$SELF.2
+GEN_DATA_DIR=releng_generated_data
+CLOG1=${GEN_DATA_DIR}/log.$SELF.1
+CLOG2=${GEN_DATA_DIR}/log.$SELF.2
 PASSED_OPTIONS=""
 
 if   [ "${1}" == "-cleanup" ]; then
@@ -15,8 +16,13 @@ elif [ "${1}" == "-rc" ]; then
  PASSED_OPTIONS="-rc"
 else
 cat << HLP
+
+runs executables from CWD starting with releng_*.
+stdout/stderr output stored in ${GEN_DATA_DIR}/log.*
+
  ${SELF} -rc [-keep]
  ${SELF} -cleanup
+
 HLP
  exit 101
 fi