docs: updated instructions

Author: fstagni

.github/CONTRIBUTING.md

@@ -1,7 +1,6 @@
 
 # Contribution Guidelines for DIRAC
 
-
 ## Pull Requests
 
 When making a `Pull Request` please explain what and why things were
@@ -12,7 +11,7 @@ relase.notes, once a new tag is made.
 Please prepend the title of your pull request with `[targetReleaseBranch]`.
 
 We are happy if you create pull-requests also if you feature is not ready, yet.
-Please mark them as such by adding `[WIP]` to the start of the title. The purpose
+Please mark them as drafts in this case. The purpose
 of this is, for example, that you want to let other people know you are working
 on a given issue. For these work-in-progress pull-request, we propose to have a
 check list of things that still need to be done.
@@ -24,9 +23,13 @@ If you notice an issue, consider first creating an issue and then refering to it
 in your pull-request and commit messages with `#[issue-id]`.
 
 ## Coding Conventions
- * You should follow the [DIRAC Coding Conventions](https://dirac.readthedocs.io/en/latest/DeveloperGuide/CodingConvention/index.html)
- * Your code should not introduce any new pylint warnings, and fix as many existing warnings as possible
+
+* You should follow the [DIRAC Coding Conventions](https://dirac.readthedocs.io/en/latest/DeveloperGuide/CodingConvention/index.html)
+* Your code should not introduce any new pylint warnings, and fix as many existing warnings as possible
 
 ## Git workflow
 
- The DIRAC Development Model is described in the [documentation](https://dirac.readthedocs.io/en/latest/DeveloperGuide/DevelopmentModel/index.html) with detailed instructions on the git workflow listed [here](https://dirac.readthedocs.io/en/latest/DeveloperGuide/DevelopmentModel/ContributingCode/index.html). For additional help on the git(hub) workflow please see this [tutorial](https://github.com/andresailer/tutorial#working-updating-pushing).
+The DIRAC Development Model is described in the [documentation](https://dirac.readthedocs.io/en/latest/DeveloperGuide/DevelopmentModel/index.html) with detailed instructions on the git workflow listed [here](https://dirac.readthedocs.io/en/latest/DeveloperGuide/DevelopmentModel/ContributingCode/index.html). For additional help on the git(hub) workflow please see this [tutorial](https://github.com/andresailer/tutorial#working-updating-pushing).
+
+Open a pull request only for the target branch. The [PR Sweeper](https://github.com/DIRACGrid/pr-sweeper) will (try to) create a PR for the "upper" branches.
+If failing to do so, an issue will be created and assigned to the PR opener.