added info about repo size

doc/workflow/importing/README.md

@@ -6,4 +6,6 @@
 4. [SVN](migrating_from_svn.md)
 
 ### Note
-* If you'd like to migrate from a self-hosted GitLab instance to GitLab.com, you can copy your repos by changing the remote and pushing to the new server; but issues and merge requests can't be imported.
\ No newline at end of file
+* If you'd like to migrate from a self-hosted GitLab instance to GitLab.com, you can copy your repos by changing the remote and pushing to the new server; but issues and merge requests can't be imported.
+
+* When you migrate repositories to GitLab, there is no restriction on maximum size. They are imported via HTTP, but if the repository is too large, it can timeout.