Update README

Author: kvablack

README.md

@@ -5,7 +5,7 @@ openpi holds open-source models and packages for robotics, published by the [Phy
 Currently, this repo contains three types of models:
 - the [π₀ model](https://www.physicalintelligence.company/blog/pi0), a flow-based vision-language-action model (VLA).
 - the [π₀-FAST model](https://www.physicalintelligence.company/research/fast), an autoregressive VLA, based on the FAST action tokenizer.
-- the [π₀.₅ model](https://www.physicalintelligence.company/blog/pi05), an upgraded version of π₀ with better open-world generalization trained with [knowledge insulation](https://www.physicalintelligence.company/research/knowledge_insulation).
+- the [π₀.₅ model](https://www.physicalintelligence.company/blog/pi05), an upgraded version of π₀ with better open-world generalization trained with [knowledge insulation](https://www.physicalintelligence.company/research/knowledge_insulation). Note that, in this repository, we currently only support the flow matching head for both $\pi_{0.5}$ training and inference.
 
 For all models, we provide _base model_ checkpoints, pre-trained on 10k+ hours of robot data, and examples for using them out of the box or fine-tuning them to your own datasets.