docs update README

README.md

@@ -42,3 +42,29 @@ This model generates some stochastic user (demands), you can simulate:
 Here you will find a gif to visualize the simulation result.
 
 ![](./PN4ECSS.gif)
+
+## How Tokens are Generated and Flow Through the Model
+
+#### 1. User Arrival and Demand (TUDi and TUDp)
+
+* Tokens representing user demand are generated at the `TUDi` and `TUDp` transitions, which simulate user arrivals at the station and park, respectively. The rate of token generation is governed by an exponential distribution based on `userPatience`.
+
+#### 2. Users Waiting (PSDi)
+
+* Arriving users are represented as tokens in the `PSDi` place, where they wait for available cars. If cars are available, tokens (users) will move to the `TUSi` transition where they pick up a car.
+
+#### 3. Car Pickup and Usage (TUSi and PCU)
+
+* Tokens (users) that successfully pick up cars move to the `PCU` place, representing cars in use by customers. This transition reduces the number of tokens in the `PSRi` place (cars ready) and increases the tokens in `PCU` (cars in use).
+
+#### 4. Car Return and Charging (TCCi, TCRi, and PSCii)
+
+* After usage, cars are returned and go through a charging process. The `TCCi` transition moves tokens from `PCU` to `PSCii` (charging state). Once charging is complete, tokens move through `TCRi` back to `PSRi` (cars ready).
+
+#### 5. Car Maintenance (TCM, TMPR, and PCM)
+
+* Occasionally, cars require maintenance. The `TCM` transition moves tokens to `PCM` (cars under maintenance). After maintenance, tokens move back to the `TMPR` transition, eventually returning to the pool of available cars.
+
+#### 6. User Departure (TUNi and TUNp)
+
+* If a user waits too long for a car, they leave the system. This is represented by the `TUNi` and `TUNp` transitions, which move tokens from the `PSDi` place without satisfying their demand.
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