Update Readme with Little Flocker info.

Added information on JZdziarski's little flocker to protect file system writes.  This software is still beta though so it might not be the best fit for the guide.  Thoughts?

README.md

@@ -923,7 +923,7 @@ Some malware comes bundled with both legitimate software, such as the [Java bund
 
 See [Methods of malware persistence on Mac OS X](https://www.virusbtn.com/pdf/conference/vb2014/VB2014-Wardle.pdf) [pdf] and [Malware Persistence on OS X Yosemite](https://www.rsaconference.com/events/us15/agenda/sessions/1591/malware-persistence-on-os-x-yosemite) to learn about how garden-variety malware functions.
 
-You could periodically run a tool like [Knock Knock](https://github.com/synack/knockknock) to examine persistent applications (e.g. scripts, binaries). But by then, it is probably too late. Maybe applications such as [Block Block](https://objective-see.com/products/blockblock.html) and [Ostiarius](https://objective-see.com/products/ostiarius.html) will help. See warnings and caveats in [issue #90](https://github.com/drduh/OS-X-Security-and-Privacy-Guide/issues/90) first, however.
+You could periodically run a tool like [Knock Knock](https://github.com/synack/knockknock) to examine persistent applications (e.g. scripts, binaries). But by then, it is probably too late. Maybe applications such as [Block Block](https://objective-see.com/products/blockblock.html) and [Ostiarius](https://objective-see.com/products/ostiarius.html) will help. See warnings and caveats in [issue #90](https://github.com/drduh/OS-X-Security-and-Privacy-Guide/issues/90) first, however.  Using an application such as [Little Flocker] (https://github.com/jzdziarski/littleflocker) can also protect parts of the filesystem from unauthorized writes similar to how Little Snitch protects the network.
 
 **Anti-virus** programs are a double-edged sword -- not useful for **advanced** users and will likely increase attack surface against sophisticated threats, however possibly useful for catching "garden variety" malware on **novice** users' Macs. There is also the additional processing overhead to consider.