Add note about SSP version compatibility in readme (#237)

Co-authored-by: Marko Ivančić <marko.ivancic@srce.hr>

Author: cicnavi

README.md

@@ -19,12 +19,17 @@ Currently supported flows are:
 
 ## Version compatibility
 
-| OIDC module | SimpleSAMLphp |  PHP   | Note                        |
-|:------------|:--------------|:------:|-----------------------------|
-| v5.\*       | v2.1.\*       | \>=8.1 | Recommended                 |
-| v4.\*       | v2.0.\*       | \>=8.0 |                             |
-| v3.\*       | v2.0.\*       | \>=7.4 | Abandoned from August 2023. |
-| v2.\*       | v1.19.\*      | \>=7.4 |                             |
+Minor versions of SimpleSAMLphp noted below means that the module has been tested with that version of SimpleSAMLphp
+during module development. SimpleSAMLphp started following semantic versioning for its API from version 2.0. This means,
+for example, that v5.* of the oidc module should work on any v2.* of SimpleSAMLphp. However, do mind that there were
+PHP version requirement changes in minor releases for SimpleSAMLphp.
+
+| OIDC module | Tested SimpleSAMLphp |  PHP   | Note                        |
+|:------------|:---------------------|:------:|-----------------------------|
+| v5.\*       | v2.1.\*              | \>=8.1 | Recommended                 |
+| v4.\*       | v2.0.\*              | \>=8.0 |                             |
+| v3.\*       | v2.0.\*              | \>=7.4 | Abandoned from August 2023. |
+| v2.\*       | v1.19.\*             | \>=7.4 |                             |
 
 ### Upgrading?