chore: add remove-signer command, fix bugs, and update release notes

- Add registry admin remove-signer command to remove a signer and all their authorizations
- Fix remove_package_signer condition (is_some -> is_none) for correct not-found error
- Use log_err() instead of silently swallowing asset fetch errors
- Trim leading '#' from version in s9pk publish path
- Add --delete-removed to s3 sync in publish-deb.sh
- Expand v0.4.0 release notes with additional features
- Regenerate man pages and add i18n entries

core/man/start-cli/start-cli-server-host-address-domain.1

@@ -2,10 +2,11 @@
 .el .ds Aq '
 .TH start-cli-server-host-address-domain 1  "domain " 
 .SH NAME
-start\-cli\-server\-host\-address\-domain
+start\-cli\-server\-host\-address\-domain \- Commands for managing host address domains
 .SH SYNOPSIS
 \fBstart\-cli server host address domain\fR [\fB\-h\fR|\fB\-\-help\fR] <\fIsubcommands\fR>
 .SH DESCRIPTION
+Commands for managing host address domains
 .SH OPTIONS
 .TP
 \fB\-h\fR, \fB\-\-help\fR
@@ -13,5 +14,7 @@ Print help
 .SH SUBCOMMANDS
 .TP
 start\-cli\-server\-host\-address\-domain\-private(1)
+Commands for managing private domains for a host
 .TP
 start\-cli\-server\-host\-address\-domain\-public(1)
+Commands for managing public domains for a host