fix(6235): added long description for the validate command (#6531)

(cherry picked from commit 3f87f78)

Author: kaanyalti

internal/pkg/agent/cmd/validate.go

@@ -17,6 +17,7 @@ func newValidateCommandWithArgs(_ []string, _ *cli.IOStreams) *cobra.Command {
 	cmd := &cobra.Command{
 		Use:           "validate",
 		Short:         "Validates the OpenTelemetry collector configuration without running the collector",
+		Long:          "Validates the OpenTelemetry collector configuration without running the collector. Validation will fail for otel-elastic hybrid configuration files. This command will return true for valid otel configurations only.",
 		SilenceUsage:  true, // do not display usage on error
 		SilenceErrors: true,
 		RunE: func(cmd *cobra.Command, _ []string) error {