check if repo is empty, create readme if it is (#45)

samples/gh-flow/src/Microsoft.AI.DevTeam/Services/GithubService.cs

@@ -80,6 +80,17 @@ public class GithubService : IManageGithub
         try
         {
             var ghRepo = await _ghClient.Repository.Get(org, repo);
+            if (ghRepo.Size == 0)
+            {
+                // Create a new file and commit it to the repository
+                var createChangeSet = await _ghClient.Repository.Content.CreateFile(
+                    org,
+                    repo,
+                    "README.md",
+                    new CreateFileRequest("Initial commit", "# Readme")
+                );
+            }
+
             await _ghClient.Git.Reference.CreateBranch(org, repo, branch, ghRepo.DefaultBranch);
         }
         catch (Exception ex)