Add PPO checkpoint metadata

models/ppo_mustard_dexpolicy_seed0.json

@@ -0,0 +1,10 @@
+{
+  "method": "PPO + DexPolicy",
+  "object": "ycb-006_mustard_bottle",
+  "seed": 0,
+  "training_budget_steps": 5000000,
+  "learning_rate": 0.00001,
+  "clip_range": 0.20,
+  "update_epochs": 5,
+  "exploration_schedule": "0.20 to 0.10 over 0-2M; 0.10 to 0.05 over 2M-4M; 0.04 thereafter"
+}