Update README.md

Author: MasloMaslane

README.md

@@ -2,7 +2,7 @@
 
 **oicompare** is a very simple program for comparing files. It works both as a
 command line utility and as a library, for example for embedding in custom
-checker programs.
+checker programs. It's used in OIOIOI when no custom checker is provided.
 
 ## Building
 
@@ -102,4 +102,4 @@ respectively that differ.
 Test data is encoded in `tests.hh`. The file `tester.cc` runs these tests both
 during compile time (as all of **oicompare** logic is `constexpr`) and during
 run time. The tester is primitive and may be expanded in the future. The API of
-the test data is currently **not stable**.
+the test data is currently **not stable**.