Fix render of bullet points of "How to do a full rebuild"

Author: traversaro

docs/Contributing.md

@@ -76,6 +76,7 @@ pixi run build
 A "full rebuild" is a rebuild of all packages for a given distro, that is typically done to update the version of ROS packages contained in a RoboStack channel, and to build against new versions of dependencies provided by conda-forge.
 
 When doing a full rebuild, please follow these guidelines:
+
 - Refresh the `rosdistro_snapshot.yaml` by running `vinca snapshot` (this is the only step that actually queries rosdistro, directly from the repo and independently from sync).
 - Refresh the `conda_build_config.yaml` file to reflect the current status of conda-forge plus migrations that are basically finished even if not updated in conda-forge-pinnings (see https://conda-forge.org/status/ for a list of ongoing migrations and their status; if in doubt, please ask the RoboStack maintainers).
 - Bump the `build_number` in `vinca_*.yaml` files to a version higher than any existing build number (considering the overriden build numbers in `pkg_additional_info.yaml`).