Remove mention of upgrade procedures

README.md

@@ -17,7 +17,6 @@ Roles:
   * [Installation](#installation)
     + [Requirements](#requirements)
     + [Installing the Collection from Ansible Galaxy](#installing-the-collection-from-ansible-galaxy)
-    + [Upgrading collection](#upgrading-collection)
   * [Usage](#usage)
   * [Supported Zabbix versions](#supported-zabbix-versions)
   * [Collection life cycle and support](#collection-life-cycle-and-support)
@@ -130,10 +129,6 @@ collections:
     version: 3.7.0
 ```
 
-### Upgrading collection
-
-Make sure to read [UPGRADE](docs/UPGRADE.md) document before installing newer version of this collection.
-
 ## Usage
 
 *Please note that these are not working examples. For documentation on how to use content included in this collection, refer to the links in the [Included content](#included-content) section.*