Link wiki page about ocamldebug in build-system.md

dev/doc/build-system.dune.md

@@ -214,6 +214,8 @@ dune exec -- dev/dune-dbg checker foo.vo
 (ocd) source db
 ```
 
+More info in the [wiki](https://github.com/coq/coq/wiki/OCamldebug).
+
 Unfortunately, dependency handling is not fully refined / automated,
 you may find the occasional hiccup due to libraries being renamed,
 etc... Please report any issue.