Updated Exit Code Mappings (markdown)

Exit-Code-Mappings.md

@@ -2,6 +2,10 @@
 
 For particular runtime environments ReCodEx can provide mappings of result codes to some custom messages. This is possible for example for Java or C# where there can be custom wrappers/runners which might catch exceptions and then provide users more detailed information about evaluations.
 
+## Free Pascal
+
+Actually, the FPC itself returns a specific code when a runtime error is encountered. All exit codes on the runtime errors list are translated into corresponding strings according to FPC documentation: [https://www.freepascal.org/docs-html/user/userap4.html](https://www.freepascal.org/docs-html/user/userap4.html)
+
 ## Java
 
 Runner: https://github.com/ReCodEx/utils/blob/master/runners/java/javarun.java