Updated Changelog (markdown)

Changelog.md

@@ -6,6 +6,9 @@ This change log tracks the releases on our [pilot server](https://recodex.mff.cu
 | 3.3.2021      |  v1.25.1 |  v1.25.1 |  v1.7.2  |  v1.3.0  |  ------  |  v1.0.0  |  v1.1.0  |
 | 3.2.2021      |  v1.25.0 |  v1.25.0 |  v1.7.2  |  v1.3.0  |  ------  |  v1.0.0  |  v1.1.0  |
 
+## TBA
+[[Major Release: ReCodEx 2.0]]
+
 ## 27.3.2021
 - CAS/LDAP registration and authentication delegated to external authentication adapter-application.