Updated submit button text in DonateMoney

src/components/DonateMoney.vue

@@ -93,7 +93,7 @@
       </div>
     </v-col>
     <div>
-      <v-btn outlined color="primary" text @click="submit()"> Send Mail </v-btn>
+      <v-btn outlined color="primary" text @click="submit()"> Send Letter </v-btn>
     </div>
   </section>
 </template>