[docs] Add Badge Typescript demo for Maximum Value (#15013)

* add typescript demo for BadgeMax
 
* format

docs/src/pages/demos/badges/BadgeMax.tsx

@@ -0,0 +1,37 @@
+import React from 'react';
+import PropTypes from 'prop-types';
+import { withStyles, Theme, createStyles, WithStyles } from '@material-ui/core/styles';
+import Badge from '@material-ui/core/Badge';
+import MailIcon from '@material-ui/icons/Mail';
+
+const styles = (theme: Theme) =>
+  createStyles({
+    margin: {
+      margin: theme.spacing(2),
+      marginRight: theme.spacing(3),
+    },
+  });
+
+function BadgeMax(props: WithStyles<typeof styles>) {
+  const { classes } = props;
+
+  return (
+    <React.Fragment>
+      <Badge className={classes.margin} badgeContent={99} color="primary">
+        <MailIcon />
+      </Badge>
+      <Badge className={classes.margin} badgeContent={100} color="primary">
+        <MailIcon />
+      </Badge>
+      <Badge className={classes.margin} badgeContent={1000} max={999} color="primary">
+        <MailIcon />
+      </Badge>
+    </React.Fragment>
+  );
+}
+
+BadgeMax.propTypes = {
+  classes: PropTypes.object.isRequired,
+} as any;
+
+export default withStyles(styles)(BadgeMax);