fix(repo): reject --repo on commands that act on no repository

tea repo list -R acme/service listed the account's repositories and
tea repo create foo -R alice/project created alice/foo: the flag was
silently ignored. repo list, repo create, repo migrate and search repo
now fail with a usage error that suggests the intended command, such as
"--repo is not used by repo list; did you mean: tea repo list acme".

repo list takes the owner as an argument (--owner still works), and
repo create accepts OWNER/NAME, creating in the organization OWNER.

Signed-off-by: bircni <bircni@icloud.com>

internal/app/help_topics.go

@@ -36,7 +36,7 @@ const (
 // help omits --repo, --remote and --cwd.
 var noRepoCommands = []string{
 	"tea admin", "tea alias", "tea auth", "tea completion", "tea config", "tea help", "tea man", "tea org",
-	"tea repo create", "tea repo list", "tea search repo", "tea ssh-key", "tea team", "tea version",
+	"tea repo create", "tea repo list", "tea repo migrate", "tea search repo", "tea ssh-key", "tea team", "tea version",
 }
 
 // writeHelp prints the help page of cmd.