mdbx-tools: minor refine built-in usage/help.

src/mdbx_drop.c

@@ -54,7 +54,9 @@ static void usage(void) {
           "usage: %s [-V] [-q] [-d] [-s name] dbpath\n"
           "  -V\t\tprint version and exit\n"
           "  -q\t\tbe quiet\n"
-          "  -d\t\tdelete the specified database, don't just empty it\n",
+          "  -d\t\tdelete the specified database, don't just empty it\n"
+          "  -s name\tdrop the specified named subDB\n"
+          "  \t\tby default empty the main DB\n",
           prog);
   exit(EXIT_FAILURE);
 }

src/mdbx_dump.c

@@ -225,10 +225,10 @@ static void usage(void) {
           "  -f\t\twrite to file instead of stdout\n"
           "  -l\t\tlist subDBs and exit\n"
           "  -p\t\tuse printable characters\n"
-          "  -a\t\tdump main DB and all subDBs,\n"
-          "    \t\tby default dump only the main DB\n"
-          "  -s\t\tdump only the named subDB\n"
-          "  -r\t\trescue mode (ignore errors to dump corrupted DB)\n",
+          "  -r\t\trescue mode (ignore errors to dump corrupted DB)\n"
+          "  -a\t\tdump main DB and all subDBs\n"
+          "  -s name\tdump only the specified named subDB\n"
+          "  \t\tby default dump only the main DB\n",
           prog);
   exit(EXIT_FAILURE);
 }

src/mdbx_load.c

@@ -485,7 +485,7 @@ static void usage(void) {
           "  -a\t\tappend records in input order (required for custom "
           "comparators)\n"
           "  -f file\tread from file instead of stdin\n"
-          "  -s name\tload into named subDB\n"
+          "  -s name\tload into specified named subDB\n"
           "  -N\t\tdon't overwrite existing records when loading, just skip "
           "ones\n"
           "  -p\t\tpurge subDB before loading\n"

src/mdbx_stat.c

@@ -61,8 +61,8 @@ static void usage(const char *prog) {
           "  -f\t\tshow GC info\n"
           "  -r\t\tshow readers\n"
           "  -a\t\tprint stat of main DB and all subDBs\n"
-          "  \t\t(default) print stat of only the main DB\n"
-          "  -s name\tprint stat of only the named subDB\n",
+          "  -s name\tprint stat of only the specified named subDB\n"
+          "  \t\tby default print stat of only the main DB\n",
           prog);
   exit(EXIT_FAILURE);
 }