added renderedtext/when repo reference

Author: mateuscap

docs/reference/conditions-reference.md

@@ -21,6 +21,8 @@ Currently, you can use the Conditions DSL to configure the following features:
 - [Skip block execution][skip]
 - [Conditionally run a block][run]
 
+You can find detailed information about the `when` operation in our [library repo](https://github.com/renderedtext/when#promote-automatically-on-master-branch-and-tags-when-the-result-is-passed).
+
 ## Formal language definition
 
 Formal language definition in [extended Backus-Naur Form (EBNF)][ebnf] notation is shown below: