done implementing AFL_MAP_SIZE

docs/env_variables.md

@@ -243,6 +243,11 @@ checks or alter some of the more exotic semantics of the tool:
     normally indicated by the cycle counter in the UI turning green. May be
     convenient for some types of automated jobs.
 
+  - AFL_MAP_SIZE sets the size of the shared map that afl-fuzz, afl-showmap,
+    afl-tmin and afl-analyze create to gather instrumentation data from
+    the target. This must be equal or larger than the size the target was
+    compiled with.
+
   - Setting AFL_NO_AFFINITY disables attempts to bind to a specific CPU core
     on Linux systems. This slows things down, but lets you run more instances
     of afl-fuzz than would be prudent (if you really want to).