[DOC] Process.last_status may return nil

[ci skip]

git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/trunk@61172 b2dd03c8-39d4-4d8f-98ff-823fe69b080e

process.c

@@ -474,7 +474,7 @@ rb_last_status_get(void)
 
 /*
  *  call-seq:
- *     Process.last_status   -> Process::Status
+ *     Process.last_status   -> Process::Status or nil
  *
  *  Return the status of the last executed child process in the
  *  current thread.