update readme, add starcoder2, cosmopedia

src/llmtuner/extras/constants.py

@@ -743,6 +743,21 @@ register_model_group(
 )
 
 
+register_model_group(
+    models={
+        "StarCoder2-3B": {
+            DownloadSource.DEFAULT: "bigcode/starcoder2-3b",
+        },
+        "StarCoder2-7B": {
+            DownloadSource.DEFAULT: "bigcode/starcoder2-7b",
+        },
+        "StarCoder2-15B": {
+            DownloadSource.DEFAULT: "bigcode/starcoder2-15b",
+        },
+    }
+)
+
+
 register_model_group(
     models={
         "Vicuna1.5-7B-Chat": {