fix typo

Author: vuittont60

tests/rustdoc-ui/error-in-impl-trait/README.md

@@ -1,5 +1,5 @@
 Each of these needs to be in a separate file,
-because the `span_delayed_bug` ICE in rustdoc won't be triggerred
+because the `span_delayed_bug` ICE in rustdoc won't be triggered
 if even a single other error was emitted.
 
 However, conceptually they are all testing basically the same thing.