Update lfs migration link

doc/topics/git/lfs/index.md

@@ -99,7 +99,7 @@ and are not pushed to the remote repository.
 
 ### Migrate an existing repository to Git LFS
 
-Read the documentation on how to [migrate an existing Git repository with Git LFS](migrate_to_git_lfs.md).
+Read the documentation on how to [migrate an existing Git repository with Git LFS](https://github.com/git-lfs/git-lfs/blob/main/docs/man/git-lfs-migrate.1.ronn).
 
 ### Removing objects from LFS