check-ignore: more output string updates

per #4323 et al.

dvc/command/check_ignore.py

@@ -41,7 +41,7 @@ def _interactive_mode(self):
             target = ask("")
             if target == "":
                 logger.info(
-                    "Empty string is not a valid pathspec. Please use . "
+                    "An empty string is not a valid path. Please use . "
                     "instead if you meant to match all paths."
                 )
                 break
@@ -101,27 +101,26 @@ def add_parser(subparsers, parent_parser):
         help="Show the exclude pattern together with each target path.",
     )
     parser.add_argument(
-        "-n",
-        "--non-matching",
+        "-a",
+        "--all",
         action="store_true",
         default=False,
-        help="Show the target paths which don’t match any pattern. "
-        "Only usable when `--details` is also employed",
+        help="Include the target paths which don’t match any pattern "
+        "in the `--details` list.",
     )
     parser.add_argument(
-        "--stdin",
+        "-n",
+        "--non-matching",
         action="store_true",
         default=False,
-        help="Read pathnames from the standard input, one per line, "
-        "instead of from the command-line.",
+        help="Include the target paths which don’t match any pattern "
+        "in the `--details` list.",
     )
     parser.add_argument(
-        "-a",
-        "--all",
+        "--stdin",
         action="store_true",
         default=False,
-        help="Show all of the patterns match the target paths. "
-        "Only usable when `--details` is also employed",
+        help="Read paths from standard input instead of providing `targets`.",
     )
     parser.add_argument(
         "targets", nargs="*", help="File or directory paths to check",