Suggest removing -- if specified, but unnecessary

[nazar-pc]

Please complete the following tasks

• I have searched the discussions
• I have searched the open and rejected issues

Clap Version

3.1.6

Describe your use case

Users are sometimes confused by help message generated by Clap in case -- was used where it was not expected:

$ ./app -- --dev --tmp
error: Found argument '--dev' which wasn't expected, or isn't valid in this context

        If you tried to supply `--dev` as a value rather than a flag, use `-- --dev`

Describe the solution you'd like

In this particular case the suggestion should be to remove -- instead of adding one more, like this:

$ ./app -- --dev --tmp
error: Found value '--dev' which wasn't expected, or isn't valid in this context

        There is an flag with the same name, try to remove `--`

Alternatives, if applicable

No response

Additional Context

No response

[epage]

Thanks for reporting this case!