Update manage_large_binaries_with_git_lfs.md

Add note to include .gitattributes file in repository - see instructions here: https://git-lfs.github.com/

doc/workflow/lfs/manage_large_binaries_with_git_lfs.md

@@ -63,6 +63,12 @@ git commit -am "Added Debian iso"     # commit the file meta data
 git push origin master                # sync the git repo and large file to the GitLab server
 ```
 
+>**Note**: Make sure that ```.gitattributes``` is tracked by git. Otherwise Git
+ LFS will not be working properly for people cloning the project.
+ ```bash
+ git add .gitattributes
+ ```
+
 Cloning the repository works the same as before. Git automatically detects the
 LFS-tracked files and clones them via HTTP. If you performed the git clone
 command with a SSH URL, you have to enter your GitLab credentials for HTTP