add naming rules to contributing (#1291)

* branch naming rules in contributing

* add motivation to branch naming rule

* formatting and typo

CONTRIBUTING.md

@@ -52,6 +52,29 @@ We use **master** branch for hot fixes (including documentation) that needs to b
 
 On the release day, **devel** branch is merged into **master**. All releases of `dlt` happen only from the **master**.
 
+### Branch naming rules
+
+We want to make sure that our git history explains in a human readable way what has been changed with which Branch or PR. To this end, we are using the following branch naming pattern (all lowercase and dashes, no underscores):
+
+```sh
+{category}/{ticket-id}-description-of-the-branch
+# example:
+feat/4922-add-avro-support
+```
+
+#### Branch categories
+
+* **feat** - a new feature that is being implemented (ticket required)
+* **fix** - a change that fixes a bug (ticket required)
+* **exp** - an experiment where we are testing a new  idea or want to demonstrate something to the team, might turn into a `feat` later (ticket encouraged)
+* **test** - anything related to the tests (ticket encouraged)
+* **blogs** - a new entry to our blog (ticket optional)
+* **docs** - a change to our docs (ticket optional)
+
+#### Ticket Numbers
+
+We encourage you to attach your branches to a ticket, if none exists, create one and explain what you are doing. For `feat` and `fix` branches, tickets are mandatory, for `exp` and `test` branches encouraged and for `blogs` and `docs` branches optional.
+
 ### Submitting a hotfix
 We'll fix critical bugs and release `dlt` out of the schedule. Follow the regular procedure, but make your PR against **master** branch. Please ping us on Slack if you do it.
 
@@ -166,3 +189,4 @@ Once the version has been bumped, follow these steps to publish the new release
 - [Poetry Documentation](https://python-poetry.org/docs/)
 
 If you have any questions or need help, don't hesitate to reach out to us. We're here to help you succeed in contributing to `dlt`. Happy coding!
+****