Release notes: Add warning about removal of single-dash arg support

[am97]

After upgrading to Caddy 2.6.1, one of my scripts unexpectedly broke because I used arguments with a single dash (I found out later that support was removed by #4565). I saw no warning in the release notes. Could you make an update to mention this breaking change ?

[mohammed90]

It was. It was mentioned in the 2.6.0 release notes, which is when it was first released. See the "Improved command line interface" section here:
https://github.com/caddyserver/caddy/releases/tag/v2.6.0

[am97]

Thanks ! (I saw the release notes for 2.6.0 in https://github.com/caddyserver/caddy/releases, but didn't realize that GitHub doesn't show them in full on that page)

[francislavoie]

Yeah, we just noticed that also. Bummer. I wish they had a more prominent Show More... button.

[mholt]

Sorry about that. Our website docs always used -- but we couldn't control the output of -h before, which showed - which was inconsistent.