Fix a couple of typos

Author: grynspan

Documentation/Proposals/NNNN-exit-tests.md

@@ -121,8 +121,8 @@ These macros take an argument of the new enumeration `ExitCondition`. This type
 describes how the child process is expected to have exited:
 
 - With a specific exit code (as passed to the C standard function `exit()` or a
-  platform equivalent;
-- With a specific signal (on POSIX-like platforms that support signal handling;
+  platform-specific equivalent);
+- With a specific signal (on POSIX-like platforms that support signal handling);
 - With any successful status; or
 - With any failure status.