Typo fix in pp.mli

Signed-off-by: Ambre Austen Suhamy <[email protected]>

src/pp.mli

@@ -55,7 +55,7 @@ val space : 'tag t
     this point. If the algorithm decides not to break the line, nothing is
     printed instead.
 
-    So for instance [verbatim "x" ++ space ++ verbatim "y"] might produce "xy"
+    So for instance [verbatim "x" ++ cut ++ verbatim "y"] might produce "xy"
     or "x\n<indentation>y". *)
 val cut : 'tag t