feat: add missing translation key

public/language/en-GB/admin/manage/categories.json

@@ -11,6 +11,7 @@
 	"num-recent-replies": "# of Recent Replies",
 	"ext-link": "External Link",
 	"is-section": "Treat this category as a section",
+	"tag-whitelist": "Tag Whitelist",
 	"upload-image": "Upload Image",
 	"delete-image": "Remove",
 	"category-image": "Category Image",

src/views/admin/manage/category.tpl

@@ -115,8 +115,8 @@
 				</fieldset>
 				<fieldset class="row">
 					<div class="col-lg-12">
-						<label for="tag-whitelist">Tag Whitelist</label><br />
-						<input id="tag-whitelist" type="text" class="form-control" placeholder="Enter category tags here" data-name="tagWhitelist" value="" />
+						<label for="tag-whitelist">[[admin/manage/categories:tag-whitelist]]</label><br />
+						<input id="tag-whitelist" type="text" class="form-control" data-name="tagWhitelist" value="" />
 					</div>
 				</fieldset>
 			</div>