chore: add language policy (#35639)

.github/ISSUE_TEMPLATE/bug-report.yml

@@ -6,7 +6,7 @@ body:
   - type: markdown
     attributes:
       value: |
-        Thank you for taking the time to file a bug report.
+        Thank you for taking the time to file a bug report. All issues must be written in English. See our [language policy](https://docs.langchain.com/oss/python/contributing/overview#language-policy).
 
         For usage questions, feature requests and general design questions, please use the [LangChain Forum](https://forum.langchain.com/).
 

.github/ISSUE_TEMPLATE/feature-request.yml

@@ -6,7 +6,7 @@ body:
   - type: markdown
     attributes:
       value: |
-        Thank you for taking the time to request a new feature.
+        Thank you for taking the time to request a new feature. All contributions must be in English. See our [language policy](https://docs.langchain.com/oss/python/contributing/overview#language-policy).
 
         Use this to request NEW FEATURES or ENHANCEMENTS in LangChain. For bug reports, please use the bug report template. For usage questions and general design questions, please use the [LangChain Forum](https://forum.langchain.com/).
 

.github/PULL_REQUEST_TEMPLATE.md

@@ -1,6 +1,9 @@
 (Replace this entire block of text)
 
 Read the full contributing guidelines: https://docs.langchain.com/oss/python/contributing/overview
+
+All contributions must be in English. See our [language policy](https://docs.langchain.com/oss/python/contributing/overview#language-policy).
+
 If you paste a large clearly AI generated description here your PR may be IGNORED or CLOSED!
 
 Thank you for contributing to LangChain! Follow these steps to have your pull request considered as ready for review.