docs: clarification on how to disable tags/filters, see #324

docs/source/tutorials/register-filters-tags.md

@@ -37,3 +37,25 @@ engine.registerFilter('add', (initial, arg1, arg2) => initial + arg1 + arg2)
 ```
 
 See existing filter implementations here: <https://github.com/harttle/liquidjs/tree/master/src/builtin/filters>
+
+## Unregister Tags/Filters
+
+In some cases it's desirable to disable some tags/filters (see [#324](https://github.com/harttle/liquidjs/issues/324)), you'll need to register a dummy tag/filter in which an corresponding Error throws.
+
+```javascript
+// disable a tag
+const disabledTag = {
+    parse: function(token) {
+        throw new Error(`tag "${token.name}" disabled`);
+    }
+}
+engine.registerTag('include', disabledTag);
+
+// disable a filter
+function disabledFilter(name) {
+    return function () {
+        throw new Error(`filter "${name}" disabled`);
+    }
+}
+engine.registerFilter('plus', disabledFilter('plus'));
+```