Merge branch 'add-documentation-for-git-operations-stack-trace' into 'master'

Adds documentation of git trace when git push/pull times out

See merge request gitlab-org/gitlab-ce!23016

doc/topics/git/troubleshooting_git.md

@@ -78,5 +78,20 @@ git push
 In case you're running an older version of Git (< 2.9), consider upgrading
 to >= 2.9 (see [Broken pipe when pushing to Git repository][Broken-Pipe]).
 
+## Timeout during git push/pull
+
+If pulling/pushing from/to your repository ends up taking more than 50 seconds,
+a timeout will be issued with a log of the number of operations performed 
+and their respective timings, like the example below:
+
+```
+remote: Running checks for branch: master
+remote: Scanning for LFS objects... (153ms)
+remote: Calculating new repository size... (cancelled after 729ms)
+```
+
+This could be used to further investigate what operation is performing poorly
+and provide GitLab with more information on how to improve the service.
+
 [SSH troubleshooting]: ../../ssh/README.md#troubleshooting "SSH Troubleshooting"
 [Broken-Pipe]: https://stackoverflow.com/questions/19120120/broken-pipe-when-pushing-to-git-repository/36971469#36971469 "StackOverflow: 'Broken pipe when pushing to Git repository'"