fix: typo when listing the number of system actors (#1315)

Co-authored-by: smagdali <[email protected]>

content/systems/filecoin_vm/sysactors/_index.md

@@ -14,7 +14,7 @@ dashboardTests: 0
 
 There are eleven (11) builtin System Actors in total, but not all of them interact with the VM. Each actor is identified by a _Code ID_ (or CID).
 
-There are two system actors required for VM processing:
+There are four (4) system actors required for VM processing:
 
 - the [InitActor](sysactors#initactor), which initializes new actors and records the network name, and
 - the [CronActor](sysactors#cronactor), a scheduler actor that runs critical functions at every epoch.