Fix/verl example (#465)

* updated verl ex

* updated script

* removed curriculum verl and updated

* updatied linting errors

* renamed

* updated config

examples/veRL/multi_env/README.md

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+# Chain Sum Training with veRL
+
+This example demonstrates how to train a language model using veRL (Volcano Engine Reinforcement Learning) with the reasoning-gym environment for chain sum problems.
+
+Requirements:
+
+python >= 3.10
+
+## Installation
+
+1. **Install veRL**: Follow the installation instructions at [veRL repository](https://github.com/volcengine/verl)
+
+2. **Install reasoning-gym**:
+   ```bash
+   pip install reasoning-gym
+   ```
+
+## Training
+
+To start training the model on chain sum problems:
+
+```bash
+python grpo_train.py --config-path config --config-name grpo_trainer
+```
+
+### Configuration
+
+You can modify the training by editing the configuration file or overriding arguments in the shell scripts directly
+
+```bash
+# Change dataset
+Here it is easiest to modify the `config/grpo_trainer.yaml` file with a custom training composite. Here is an example experiment which uses a composite of algorithmic training tasks
+```yaml
+reasoning_gym:
+  dataset_size: 20000
+  developer_prompt: DeepSeekZero
+  datasets:
+    ab:
+      weight: 1
+    base_conversion:
+      weight: 1
+    binary_alternation:
+      weight: 1
+      config:
+        p_solvable: 0.9
+    binary_matrix:
+      weight: 1
+      config:
+        min_n: 2
+        max_n: 6
+    caesar_cipher:
+      weight: 1
+      config:
+        max_words: 10
+    cryptarithm:
+      weight: 1
+    isomorphic_strings:
+      weight: 1
+      config:
+        max_string_length: 8
+```
+
+# Change configuration Set project_name and experiment_name if logging your runs to W&B. T
+This config assumes a single GPU node, but you can configure this too. The following command would be for 2 GPUs, with 1 used for vLLM rollouts:
+
+python3 -u train_grpo.py --config-paths configs/inter_generalisation --config-name algorithmic_qwen_3b \
+    actor_rollout_ref.rollout.tensor_model_parallel_size=1 \
+    trainer.n_gpus_per_node=2 \
+    trainer.project_name=rg-grpo \
+    trainer.experiment_name=algorithmic_qwen2.5_3b
+
+Or similarly you could define this in a config file directly