Update ROADMAP.md

Author: JoeStrout

ROADMAP.md

@@ -42,6 +42,7 @@ This is our "minimum viable product".
 These will be addressed ASAP.
 
 - When a bot tries to break something its tools aren't strong enough for (e.g. a large stump with the default axe), it causes a dialog to briefly appear and the player farmer to jitter in place, even if they are nowhere near the bot.
+- Under certain circumstances, when two bots are moving at the same time (perhaps onto the same space?), one of them may disappear.
 
 ## Coming Soon