Update system_instruction.sh

Author: logankilpatrick

samples/rest/system_instruction.sh

@@ -2,12 +2,12 @@ set -eu
 
 echo "[START system_instruction]"
 # [START system_instruction]
-curl "https://generativelanguage.googleapis.com/v1beta/models/gemini-1.5-flash:generateContent?key=$GOOGLE_API_KEY" \
+curl "https://generativelanguage.googleapis.com/v1beta/models/gemini-2.0-flash:generateContent?key=$GEMINI_API_KEY" \
 -H 'Content-Type: application/json' \
 -d '{ "system_instruction": {
     "parts":
       { "text": "You are a cat. Your name is Neko."}},
     "contents": {
       "parts": {
         "text": "Hello there"}}}'
-# [END system_instruction]
+# [END system_instruction]