Add link to code repository

This PR adds a link to the GitHub repository containing the code for the PDS-1B model. This makes it easier for users to access the code
and reproduce the results presented in the paper.

README.md

@@ -1,11 +1,11 @@
 ---
-license: apache-2.0
 datasets:
 - togethercomputer/RedPajama-Data-1T
 language:
 - en
-pipeline_tag: text-generation
 library_name: transformers
+license: apache-2.0
+pipeline_tag: text-generation
 ---
 
 ## PDS-1B
@@ -51,4 +51,4 @@ PDS-selected data improves the performance of language models pre-trained from s
   journal={arXiv preprint arXiv:2410.07064},
   year={2024}
 }
-```
+```