Object upgrade notice for 3.7.0 changelog

See https://forum.silverstripe.org/t/php-7-2-backwards-compat-for-module-maintainers-on-ss-3-7/464/5

docs/en/04_Changelogs/3.7.0.md

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+# 3.7.0 (unreleased)
+
+## SilverStripe 3.7 and PHP 7.2 and Object subclasses
+
+### For Project Code
+
+SilverStripe 3.7 now supports PHP 7.2, which is exciting, but PHP 7.2 introduces an `object` keyword.
+To use it, you can replace any uses of `Object` with `SS_Object` in your own project code.
+
+```diff
+-class MyClass extends Object
++class MyClass extends SS_Object
+{
+	public function myFunction()
+	{
+-		$foo = Object::has_extension('MyExtension');
++		$foo = SS_Object::has_extension('MyExtension');
+	}
+}
+```
+
+You are also reliant on any SilverStripe modules directly using `Object` to upgrade their codebase.
+Matches for `SS_Object` in the module codebase will tell you it's been upgraded.
+A search for `extends Object` or `Object::` isn't fool proof, but will give you an indication
+that the module still needs to be upgraded. If in doubt, check the module README.
+
+### For Module Authors
+
+If you are publishing a 3.x-compatible module that directly references the `Object` class,
+we recommend that you replace all references to `Object` with `SS_Object`,
+and add the following line to your module's `_config.php`
+in order to support both current SilverStripe 3.x and SilverStripe 3.7 releases running on PHP 7.2:
+
+```php
+// Ensure compatibility with PHP 7.2 ("object" is a reserved word),
+// with SilverStripe 3.6 (using Object) and SilverStripe 3.7 (using SS_Object)
+if (!class_exists('SS_Object')) class_alias('Object', 'SS_Object');
+```
+
+Don't forget to mention explicit PHP 7.2 and SilverStripe 3.7 compatibility in your module README.
+
+Note that in SilverStripe 4.x, the `Object` class was deleted so there isn’t an `SS_Object` class there either
+(see [https://docs.silverstripe.org/en/4/changelogs/4.0.0/](changelog))