Added note about updating pull requests by force push

- Added note about force pushing same branch to update a existing pull
  request instead of opening new one in contributing guide.
- [ci skip]

1 files changed, 17 insertions, 0 deletions

diff --git a/guides/source/contributing_to_ruby_on_rails.md b/guides/source/contributing_to_ruby_on_rails.md
index 8bc4b10591..0266a92d07 100644
--- a/guides/source/contributing_to_ruby_on_rails.md
+++ b/guides/source/contributing_to_ruby_on_rails.md
@@ -559,6 +559,23 @@ $ git push origin my_pull_request -f
 You should be able to refresh the pull request on GitHub and see that it has
 been updated.
 
+#### Updating pull request
+
+Sometimes you will be asked to make some changes to the code you have
+already committed. This can include amending existing commits. In this
+case git will not allow you to push the changes as the pushed version
+and local version does not match. Instead of opening new pull request,
+you can force push to your branch on Github like described earlier in
+squashing commits section:
+
+```bash
+$ git push origin my_pull_request -f
+```
+
+This will update the branch on Github with your new code and
+Github will take care of updating the pull request with new code.
+
+
 ### Older Versions of Ruby on Rails
 
 If you want to add a fix to older versions of Ruby on Rails, you'll need to set up and switch to your own local tracking branch. Here is an example to switch to the 4-0-stable branch: