docs: 更新了英文的README (#38)

* Update README_en.md

* Update README_en.md

* Update README_en.md

* Update README_en.md

* Update README_en.md

README_en.md

@@ -63,7 +63,13 @@ docker run -d -p 3000:3000 \
   14790897/paperai:latest
 ```
 
-Replace `CUSTOM_AI_URL` and `CUSTOM_API_KEY` to your own model path and API key
+Replace `CUSTOM_AI_URL` and `CUSTOM_API_KEY` to your own AI URL and API key
+
+## Environment variable description
+1. NEXT_PUBLIC_OPENAI_API_KEY sets the key. Simply leave the corresponding position in the settings interface (the gear in the upper right corner) blank, the predetermined variable will be used.
+2. NEXT_PUBLIC_AI_URL sets the upstream url. Simply leave the corresponding position in the settings interface (the gear in the upper right corner)  blank, the predetermined variable will be used.
+3. NEXT_PUBLIC_SEMANTIC_API_KEY sets the `semantic scholar` key to increase the number of requests
+4. NEXT_PUBLIC_PUBMED_API_KEY sets the `pubmed` key to increase the number of requests
 
 ## Clone and run locally
 
@@ -82,6 +88,12 @@ npm run dev
 
  ```
 
+## Reference
+
+1. semantic scholar api: https://api.semanticscholar.org/api-docs/#tag/Paper-Data/operation/get_graph_paper_relevance_search
+2. pubmed api: https://www.ncbi.nlm.nih.gov/books/NBK25500/
+3. i18n: https://locize.com/blog/next-app-dir-i18n/
+
 ## LICENSE
 This repository is licensed under the MIT License