Update placeholder text and color

src/css/_form.scss

@@ -26,6 +26,10 @@ input {
     border-style: solid;
     border-width: 1px;
     min-height: 20px;
+
+    &::placeholder {
+      color: #ccc;
+    }
   }
 
   .text-muted {

src/js/components/Form.js

@@ -128,7 +128,7 @@ class Form extends Component {
             name="description"
             onChange={onChange}
             value={changeset.description}
-            placeholder="Beschreibung der Tätigkeit - mind. 3 Zeichen"
+            placeholder="Beschreibung der Tätigkeit – optional"
             maxLength={255}
             rows={3}
             onKeyDown={this.handleTextareaKeyDown}