Guide transition from --dev (#7647)

Author: niccokunzmann

src/poetry/console/commands/add.py

@@ -30,7 +30,10 @@ class AddCommand(InstallerCommand, InitCommand):
         option(
             "dev",
             "D",
-            "Add as a development dependency. (<warning>Deprecated</warning>)",
+            (
+                "Add as a development dependency. (<warning>Deprecated</warning>) Use"
+                " --group=dev instead."
+            ),
         ),
         option("editable", "e", "Add vcs/path dependencies as editable."),
         option(

src/poetry/console/commands/remove.py

@@ -24,6 +24,7 @@ class RemoveCommand(InstallerCommand):
             (
                 "Remove a package from the development dependencies."
                 " (<warning>Deprecated</warning>)"
+                " Use --group=dev instead."
             ),
         ),
         option(