dev: fix example.env make it less confusing

Author: thirdgerb

ghostos/app/.example.env

@@ -4,14 +4,14 @@
 # or export the values to environment.
 
 # [openai](https://openai.com/) api key
-OPENAI_API_KEY
+OPENAI_API_KEY="your openai key"
 # optional openai proxy
-OPENAI_PROXY
+OPENAI_PROXY="your openai proxy"
 # [moonshot](https://moonshot.cn/) api key
 MOONSHOT_API_KEY="your moonshot model api key"
 # [anthropic](https://www.anthropic.com/) api key
 ANTHROPIC_API_KEY="your anthropic api key"
 # optional anthropic proxy
-ANTHROPIC_PROXY
+#ANTHROPIC_PROXY
 # [deepseek](https://deepseek.com) api key
-DEEPSEEK_API_KEY
+DEEPSEEK_API_KEY="your deepseek api key"