[legacy] update legacy README file

Add info about newly tested systems Fedora 41, Ubuntu 24.04 and OpenSuse 15.5.
All three are not yet in the test matrix such that an extra paragraph in the
README file was added for systems which were tested only manually.
Debian 10 and Debian 12 were also tested with the changes and the installation
is working.

legacy/README.md

@@ -100,6 +100,17 @@ please contact us.
 | Ubuntu     | x86_64 | 20.04 | GCC 9.4.0                  | 3.24.3 (`bootstrap-cmake.sh`) |
 | Ubuntu     | x86_64 | 22.04 | GCC 11.3.0                 | 3.22.1 |
 
+The following systems are not in the test matrix and therefore are not tested
+regularly. They were at least build successful once doing the same steps as
+executed for the regular tests. They maybe will be added to the test matrix
+for newer versions of FairSoft. 
+
+| **OS Name** | **Arch** | **OS Version** | **Compiler** | **CMake** |
+| --- | --- | --- | --- | --- |
+| Fedora     | x86_64 | 41    | GCC 14.2.1                 | 3.30.5 |
+| OpenSuSe   | x86_64 | 15.5  | GCC 7.5.0                  | 3.20.4 |
+| Ubuntu     | x86_64 | 24.04 | GCC 13.2.0                 | 3.28.3 |
+
 ## Included packages
 
 | **Package** | **Version** | **URL** |