docs: update README

Author: Tonidotpy

README.md

@@ -38,9 +38,26 @@ The main interface to the FSM in C is the `run_state` function. See at the end o
 
 If you need an FSM for your Arduino, you can generate it with the command option `--ino`: this will generate a `.h` and a `.cpp` files, omitting all instructions that are not available on the Arduino (e.g. the `syslog` calls, which are replaced with `Serial.print calls`). Load these files in the IDE, require the header from the main `.ino` file, and call the FSM manager function from within the main `loop()` function.
 
+## NEW in version 0.4
+
+GV_FSM version 0.4.0 introduces a new mechanism to trigger state changes from outside the FSM using events.
+
+The `event_data_t` typedef, like `state_data_t`, can be used to pass custom data when a new event is triggered.
+
+Two functions are generated by default to trigger a new event or check if one is already fired.
+To change state when the event is triggered an explicit check has to be made inside of a state function, for example:
+
+```c
+if (is_event_triggered())
+    next_state = STATE_NEXT;
+```
+
+> [!IMPORTANT]
+> Only one event at a time can be fired.
+
 ## NEW in version 0.3
 
-Gem version o.3.0 introduces a new CLI option that enables the generation of code that support SIGINT signal management:
+GV_FSM version 0.3.0 introduces a new CLI option that enables the generation of code that support SIGINT signal management:
 
 ```bash
 gv_fsm fsm.dot -k stop

lib/version.rb

@@ -1,3 +1,3 @@
 module GV_FSM
-  VERSION = "0.4.4"
+  VERSION = "0.4.0"
 end