doc: touch: clarify --time description in man page

* src/touch.c (usage): Reorganise the description to be similar to
the format used for the ls --time description, which formats better
when converted to a man page.  Also separate the description
to allow for more granular translations.
Fixes https://bugs.gnu.org/67656

src/touch.c

@@ -240,9 +240,11 @@ change the times of the file associated with standard output.\n\
       fputs (_("\
   -r, --reference=FILE   use this file's times instead of current time\n\
   -t STAMP               use [[CC]YY]MMDDhhmm[.ss] instead of current time\n\
-      --time=WORD        change the specified time:\n\
-                           WORD is access, atime, or use: equivalent to -a\n\
-                           WORD is modify or mtime: equivalent to -m\n\
+"), stdout);
+      fputs (_("\
+      --time=WORD        specify which time to change:\n\
+                           access time (-a): 'access', 'atime', 'use';\n\
+                           modification time (-m): 'modify', 'mtime'\n\
 "), stdout);
       fputs (HELP_OPTION_DESCRIPTION, stdout);
       fputs (VERSION_OPTION_DESCRIPTION, stdout);