cmd/rcd: Fix command docs to include command specific prefix (#6675)

This change addresses two issues with commands that re-used
flags from common packages:

1) cobra.Command definitions did not include the command specific
   prefix in doc strings.
2) Command specific flag prefixes were added after generating
   command doc strings.

lib/http/auth_test.go

@@ -0,0 +1,15 @@
+package http
+
+import (
+	"strings"
+	"testing"
+)
+
+func TestHelpPrefixAuth(t *testing.T) {
+	// This test assumes template variables are placed correctly.
+	const testPrefix = "server-help-test"
+	helpMessage := AuthHelp(testPrefix)
+	if !strings.Contains(helpMessage, testPrefix) {
+		t.Fatal("flag prefix not found")
+	}
+}