feature: SERVERUS_ROOT environment variable

README.md

@@ -46,6 +46,11 @@ The default handlers are:
 You just start serverus in a directory (or specify a root) and it tells you where it's
 listening.
 
+## Environment Variables
+
+ - `SERVERUS_ROOT`: set the root, aka --root on the command line
+ - `SERVERUS_HANDLERS`: a list of ;-separated directories to look for handlers in
+
 ### Typescript Handling
 
 These types and interface define the default serverus Typescript handler's expected