README: add a note about repo status

README.md

@@ -1,5 +1,8 @@
 ## MGen
 
+### N.B.: This work will soon be under submission.
+Please do not share this repo too widely yet to help maintain double-blind reviewing.
+
 MGen is a set of tools for generating simulated messenger traffic.
 It is designed for use analogous to (and likely in conjunction with) [TGen](https://github.com/shadow/tgen), but for simulating traffic generated from communications in messenger apps, such as Signal or WhatsApp, rather than web traffic or file downloads.
 Notably, this allows for studying network traffic properties of messenger apps in [Shadow](https://github.com/shadow/shadow).