Fix error message and improve help text

Author: Mr-Pepe

news/3297dfd6-b078-4452-97a1-7d2c1ab41ca1.trivial.rst

@@ -103,7 +103,10 @@ def add_options(self) -> None:
             dest="list_format",
             default="columns",
             choices=("columns", "freeze", "json"),
-            help="Select the output format among: columns (default), freeze, or json",
+            help=(
+                "Select the output format among: columns (default), freeze, or json. "
+                "The 'freeze' format cannot be used together with the --outdated option."
+            ),
         )
 
         self.cmd_opts.add_option(
@@ -157,7 +160,7 @@ def run(self, options: Values, args: List[str]) -> int:
 
         if options.outdated and options.list_format == "freeze":
             raise CommandError(
-                "List format 'freeze' can not be used with the --outdated option."
+                "List format 'freeze' cannot be used together with the --outdated option."
             )
 
         cmdoptions.check_list_path_option(options)

src/pip/_internal/commands/list.py

@@ -588,7 +588,7 @@ def test_outdated_formats(script: PipTestEnvironment, data: TestData) -> None:
         expect_error=True,
     )
     assert (
-        "List format 'freeze' can not be used with the --outdated option."
+        "List format 'freeze' cannot be used together with the --outdated option."
         in result.stderr
     )