Added entries about deprecation of old server and type resolution strategies to UPGRADE.md document

Author: vladar

UPGRADE.md

@@ -139,6 +139,12 @@ $schema->assertValid();
 ``` 
 See https://github.com/webonyx/graphql-php/issues/148
 
+### Deprecated: experimental `GraphQL\Server`
+Use [new PSR-7 compliant implementation](docs/executing-queries.md#using-server) instead.
+
+### Deprecated: experimental `GraphQL\Type\Resolution` interface and implementations
+Use schema [**typeLoader** option](docs/type-system/schema.md#lazy-loading-of-types) instead.
+
 ### Non-breaking: usage on async platforms
 When using the library on async platforms use separate method `GraphQL::promiseToExecute()`. 
 It requires promise adapter in it's first argument and always returns a `Promise`.