Update the single purpose on the git etiquette

orgs/essays/git-etiquette.org

@@ -38,6 +38,24 @@ Commits are the building blocks of version controlling via Git. It's obvious tha
 quality will result in improvement in the overall quality of the repository.
 
 ** Single purpose commits
+Oftentimes engineers working on something get sidetracked into doing too many things when working on
+one particular thing like when you are trying to fix one particular bug and you spot another one,
+and you can’t resist the urge to fix that as well. And another one. Soon, it snowballs and you end
+up with so many changes all going together in one commit.
+
+This is problematic, and it is better to keep commits as small and focused as possible for many
+reasons, including:
+
+- It makes it easier for other people in the team looking at your change, making code reviews
+  more efficient.
+- If the commit has to be rolled back completely, it’s far easier to do so.
+- It's straightforward to track these changes with your ticketing system.
+- It helps you mentally parse changes you’ve made using git log.
+
+A commit should be a wrapper for related changes. For example, fixing two different bugs should
+produce two separate commits. Small commits make it easier for other team members to understand
+the changes and roll them back if something went wrong. With tools like the staging area and the
+ability to stage only parts of a file, Git makes it easy to create very granular commits.
 
 ** Commit Messages
 On many occasions we need to inspect the *Git* history to find something. A commit, specific changes,