Add a translation.

public/locales/en.json

@@ -1,5 +1,6 @@
 {
   "invoices": {
-    "title": "Invoices"
+    "title": "Invoices",
+    "new_invoice": "New invoice"
   }
 }

public/locales/est.json

@@ -1,5 +1,6 @@
 {
   "invoices": {
-    "title": "Arved"
+    "title": "Arved",
+    "new_invoice": "Uus arve"
   }
 }

src/views/dashboard/Invoices.vue

@@ -4,7 +4,7 @@
             <div class="col-12 mb-4 pr-0 d-flex justify-content-between">
                 <h4 class="mb-0">{{ $t('title') }}</h4>
                 <div>
-                    <button class="btn btn-sm btn-outline-dark" @click="createNewInvoice">New invoice</button>
+                    <button class="btn btn-sm btn-outline-dark" @click="createNewInvoice">{{ $t('new_invoice') }}</button>
                     <b-dropdown variant="link" size="sm" no-caret right>
                         <template slot="button-content">
                             <i class="material-icons">more_vert</i>