Update readme

Signed-off-by: Jael Gu <mengjia.gu@zilliz.com>

README.md

@@ -53,7 +53,13 @@ Create the operator via the following factory method
 
 The model name in string.
 The default value is "allenai/longformer-base-4096".
-You can get the list of supported model names by calling `get_model_list` from [longformer.py](https://towhee.io/text-embedding/longformer/src/branch/main/longformer.py).
+
+Supported model names:
+- allenai/longformer-base-4096
+- allenai/longformer-large-4096
+- allenai/longformer-large-4096-finetuned-triviaqa
+- allenai/longformer-base-4096-extra.pos.embd.only
+- allenai/longformer-large-4096-extra.pos.embd.only
 
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