docs: add comment for TooltipChild

src/components/TooltipChild.tsx

@@ -1,5 +1,10 @@
 import { forwardRef, PropsWithChildren } from 'react'
 
+/**
+ * Helper wrapper for custom child components when using `@mui/material/tooltips`.
+ * Mui Tooltip works out-the-box with other `@mui` components but when using custom they require ref.
+ * @source https://mui.com/material-ui/react-tooltip/#custom-child-element
+ */
 export const TooltipChild = forwardRef<HTMLSpanElement, PropsWithChildren>(
   ({ children, ...rest }, ref) => {
     return (