Add a tip to help with NWFilter priorities

virtweb_frontend/src/widgets/forms/NWFilterPriorityInput.tsx

@@ -16,6 +16,7 @@ export function NWFilterPriorityInput(p: {
         p.onChange?.(v && v !== "" ? Number(v) : undefined);
       }}
       size={ServerApi.Config.constraints.nwfilter_priority}
+      helperText="A lower priority value is accessed before one with a higher value"
     />
   );
 }

virtweb_frontend/src/widgets/forms/TextInput.tsx

@@ -16,6 +16,7 @@ export function TextInput(p: {
   maxRows?: number;
   type?: React.HTMLInputTypeAttribute;
   style?: React.CSSProperties;
+  helperText?: string;
 }): React.ReactElement {
   if (!p.editable && (p.value ?? "") === "") return <></>;
 
@@ -54,7 +55,7 @@ export function TextInput(p: {
       minRows={p.minRows}
       maxRows={p.maxRows}
       error={valueError !== undefined}
-      helperText={valueError}
+      helperText={valueError ?? p.helperText}
     />
   );
 }