add input compacting guide

Author: atanas-dev

documentation/1-guides/70-compacting-input-vars.md

@@ -0,0 +1,12 @@
+# Compacting input variables to fit within PHP's max_input_vars
+
+In some cases forms can end up having hundreds of inputs which can cause the save request to exceed PHP's `max_input_vars` limit leading to lost request data. To combat this, Carbon Fields comes with a built-in support for input compacting which causes all inputs created by Carbon Fields to be sent as a single input var.
+
+To enable input compacting please add the following near the top of your functions.php:
+```php
+// Enables input var compacting
+define( 'Carbon_Fields\\COMPACT_INPUT', true );
+
+// Optionally overrides the compacted input name. You do not need this in most cases.
+define( 'Carbon_Field\\COMPACT_INPUT_KEY', 'my_custom_compacted_input_name' );
+```

documentation/1-guides/README.md

@@ -13,8 +13,9 @@ Carbon Fields - Docs
 * [Predefined Complex Groups](https://github.com/htmlburger/carbon-fields-docs/tree/master/documentation/20-predefined-complex-groups.md)
 * [Sidebar Options](https://github.com/htmlburger/carbon-fields-docs/tree/master/documentation/1-guides/30-sidebar-options.md)
 * [Serialized Datastore](https://github.com/htmlburger/carbon-fields-docs/tree/master/documentation/50-serialized-datastore.md)
-* [Serialized Datastore](https://github.com/htmlburger/carbon-fields-docs/tree/master/documentation/60-bedrock-support.md)
+* [Bedrock Support](https://github.com/htmlburger/carbon-fields-docs/tree/master/documentation/60-bedrock-support.md)
+* [Compacting Input Vars](https://github.com/htmlburger/carbon-fields-docs/tree/master/documentation/70-compacting-input-vars.md)
 
 ---
 
-**[< Back to Documentation Home](https://github.com/htmlburger/carbon-fields-docs/tree/master/documentation)**
+**[< Back to Documentation Home](https://github.com/htmlburger/carbon-fields-docs/tree/master/documentation)**