ChatOn: update sample meta json a bit

Move [inst] [/inst] wrt llama2 from global to individual role
specific parts.

Avoid an extra \n wrt prefixes of llama3

examples/chaton_meta.json

@@ -2,17 +2,17 @@
 {
 	"llama2": {
 		"global": {
-			"prefix": "[INST] ",
-			"suffix": " [/INST]"
-		},
-		"system": {
-			"prefix": " <<SYS>>\n",
-			"suffix": "\n<</SYS>>\n\n"
-		},
-		"user": {
 			"prefix": "",
 			"suffix": ""
 		},
+		"system": {
+			"prefix": "[INST] <<SYS>>\n",
+			"suffix": "\n<</SYS>> [/INST]\n\n"
+		},
+		"user": {
+			"prefix": "[INST] ",
+			"suffix": " [/INST]\n\n"
+		},
 		"assistant": {
 			"prefix": "",
 			"suffix": ""
@@ -25,15 +25,15 @@
 			"suffix": ""
 		},
 		"system": {
-			"prefix": "<|start_header_id|>system<|end_header_id|>\n\n",
+			"prefix": "<|start_header_id|>system<|end_header_id|>\n",
 			"suffix": "<|eot_id|>\n\n"
 		},
 		"user": {
-			"prefix": "<|start_header_id|>user<|end_header_id|>\n\n",
+			"prefix": "<|start_header_id|>user<|end_header_id|>\n",
 			"suffix": "<|eot_id|>\n\n"
 		},
 		"assistant": {
-			"prefix": "<|start_header_id|>assistant<|end_header_id|>\n\n",
+			"prefix": "<|start_header_id|>assistant<|end_header_id|>\n",
 			"suffix": ""
 		},
 		"reverse-prompt": "<|eot_id|>"