[docs] wenet model docs (#2220)

* update README.md

* update wenet/README.md

* update wenet model simple introduction

* fixed

* add remove trailing whitespace

* fixed

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Co-authored-by: shanguanma <[email protected]>

wenet/README.md

@@ -16,7 +16,9 @@ Here is a brief introduction of each module(directory).
 * `efficient_conformer`: efficient conformer implementation, please refer [paper](https://arxiv.org/pdf/2109.01163.pdf)
 * `cif`: Continuous Integrate-and-Fire implemented, please refer [paper](https://arxiv.org/pdf/1905.11235.pdf)
 * `branchformer`: branchformer implementation, please refer [paper](https://arxiv.org/abs/2207.02971)
-
+* `whisper`: whisper implementation, please refer [paper](https://arxiv.org/abs/2212.04356)
+* `ssl`: Self-supervised speech model implementation. e.g. wav2vec2, bestrq, w2vbert.
+* `ctl_model`: Enhancing the Unified Streaming and Non-streaming Model with  with Contrastive Learning implementation [paper](https://arxiv.org/abs/2306.00755)
 
 `transducer`, `squeezeformer`, `efficient_conformer`, `branchformer` and `cif` are all based on `transformer`,
 they resue a lot of the common blocks of `tranformer`.