Added --abort

Command-line.md

@@ -60,6 +60,16 @@ In addition to the command line option, ensure you have built your code with the
 Usually you only want to see reporting for failed tests. Sometimes it's useful to see *all* the output (especially when you don't trust that that test you just added worked first time!).
 To see successul, as well as failing, test results just pass this option.
 
+## Aborting after a certain number of failures
+<pre>
+-a, --abort [&lt;failure threshold>]
+</pre>
+
+If a REQUIRE assertion fails the test case aborts, but subsequent test cases are still run.
+If a CHECK assertion fails even the current test case is not aborted.
+
+Sometimes this results in a flood of failure messages and you'd rather just see the first few. Specifying -a or --abort on its own will abort the whole test run on the first failed assertion of any kind. Following it with a number causes it to abort after that number of assertion failures.
+
 ## Listing available tests or reporters
 <pre>
 -l, --list [tests | reporters] [xml]