Please make the branch name variable available in PR Template

Jiwon Jeon_dmugch

I want to insert the following command onto PR Template.

```shell
BRANCH={{branch_name}}; git fetch origin $BRANCH; git pull; git checkout $BRANCH;
```

To achieve this, a new variable including branch name must be created.

Theodora Boudale

Hi @Jiwon Jeon,

You can use the special variables {{source_branch}} and {{destination_branch}} in the Default pull request description in order to refer to the PR's branches.

I will ask the team that maintains the documentation to update our docs and include these variables as well.

Please feel free to reach out if you have any questions.

Kind regards,
Theodora