[JOSS] Docs: Clarify difference between core and user examples (#2706)

This PR updates the README for the Mesa core examples to better explain the distinction between:

1. Core examples in the main Mesa repository - maintained by the Mesa team and demonstrating key ABM concepts
2. User-contributed examples in the mesa-examples repository - community showcases and additional implementations

Author: EwoutH

mesa/examples/README.md

@@ -1,7 +1,12 @@
-# Mesa core examples
-These examples are a collection of classic agent based models built using Mesa. These core examples are maintained by the Mesa team and are intended to demonstrate the capabilities of Mesa.
+# Mesa Core Examples
+This repository contains a curated set of classic agent-based models implemented using Mesa. These core examples are maintained by the Mesa development team and serve as both demonstrations of Mesa's capabilities and starting points for your own models.
 
-More user examples and showcases can be found in the [mesa-examples](https://github.com/projectmesa/mesa-examples) repository.
+## Overview
+The examples are categorized into two groups:
+1. **Basic Examples** - Simpler models that use only stable Mesa features; ideal for beginners
+2. **Advanced Examples** - More complex models that demonstrate additional concepts and may use some experimental features
+
+> **Note:** Looking for more examples? Visit the [mesa-examples](https://github.com/projectmesa/mesa-examples) repository for user-contributed models and showcases.
 
 ## Basic Examples
 The basic examples are relatively simple and only use stable Mesa features. They are good starting points for learning how to use Mesa.
@@ -34,4 +39,4 @@ Grid-based demographic prisoner's dilemma model, demonstrating how simple rules
 This is Epstein & Axtell's Sugarscape model with Traders, a detailed description is in Chapter four of *Growing Artificial Societies: Social Science from the Bottom Up (1996)*. The model shows how emergent price equilibrium can happen via decentralized dynamics.
 
 ### [Wolf-Sheep Predation Model](examples/advanced/wolf_sheep)
-Implementation of an ecological model of predation and reproduction, based on the NetLogo [Wolf Sheep Predation](http://ccl.northwestern.edu/netlogo/models/WolfSheepPredation) model.
+Implementation of an ecological model of predation and reproduction, based on the NetLogo [Wolf Sheep Predation](http://ccl.northwestern.edu/netlogo/models/WolfSheepPredation) model.