llvm-openmp: mention potential cause of the armv8 Debug issues

As suggested by @marxin at conan-io#19857 (comment)

recipes/llvm-openmp/all/conanfile.py

@@ -97,8 +97,9 @@ def validate(self):
         if is_apple_os(self) and self.settings.arch == "armv8":
             if self._version_major <= 10:
                 raise ConanInvalidConfiguration("ARM v8 not supported")
-            if self._version_major != 11 and self.settings.build_type == "Debug":
+            if self._version_major >= 12 and self.settings.build_type == "Debug":
                 # All versions except for v11 crash with a segfault for the simple test_package.cpp test
+                # Might be related to https://github.com/llvm/llvm-project/issues/49923
                 raise ConanInvalidConfiguration("Debug mode not supported for ARM v8")
 
     def build_requirements(self):