chore: add Serbian to doc and rename the file (#12150)

packages/vant/src/locale/README.md

@@ -67,6 +67,7 @@ Current supported languages:
 | Portuguese (Brazil)      | pt-BR        | `v3.3.3` |
 | Romanian                 | ro-RO        | -        |
 | Russian                  | ru-RU        | `v3.1.5` |
+| Serbian                  | sr-RS        | `v4.6.4` |
 | Swedish                  | sv-SE        | `v3.4.7` |
 | Thai                     | th-TH        | -        |
 | Turkish                  | tr-TR        | -        |

packages/vant/src/locale/README.zh-CN.md

@@ -68,6 +68,7 @@ Locale.add(messages);
 | 葡萄牙语（巴西）     | pt-BR        | `v3.3.3` |
 | 罗马尼亚语           | ro-RO        | -        |
 | 俄罗斯语             | ru-RU        | `v3.1.5` |
+| 塞尔维亚语           | sr-RS        | `v4.6.4` |
 | 瑞典语               | sv-SE        | `v3.4.7` |
 | 泰语                 | th-TH        | -        |
 | 土耳其语             | tr-TR        | -        |

packages/vant/src/locale/lang/sr-RS.ts

@@ -15,7 +15,15 @@ export default {
     end: 'Završetak',
     start: 'Početak',
     title: 'Izaberite Datum',
-    weekdays: ['Nedelja', 'Ponedeljak', 'Utorak', 'Sreda', 'Četvrtak', 'Petak', 'Subota'],
+    weekdays: [
+      'Nedelja',
+      'Ponedeljak',
+      'Utorak',
+      'Sreda',
+      'Četvrtak',
+      'Petak',
+      'Subota',
+    ],
     monthTitle: (year: number, month: number) => `${year}/${month}`,
     rangePrompt: (maxRange: number) => `Izaberite do ${maxRange} dana`,
   },