C++: Fix QLDoc

Author: jketema

cpp/ql/lib/semmle/code/cpp/ConfigurationTestFile.qll

@@ -7,7 +7,7 @@
 import File
 
 /**
- * Models a file created to test the system configuration.
+ * A file created to test the system configuration.
  */
 abstract class ConfigurationTestFile extends File { }