Add recommendations about gitignore usage

Background

As discussed in apertis-infrastructure!223 (merged) it is useful to have clear guidelines on how to use gitignore, and other configurations to follow the same rules across repositories.

Outcomes

TBD

Management data

This section is for management only, it should be the last one in the description.

/cc @em @Balasubramanian @sudarshan @wlozano

Phabricator link: https://phabricator.apertis.org/T10830

added priority:needs triage release:v2023 release:v2024 release:v2025pre status:unconfirmed labels

assigned to @wlozano

mentioned in merge request apertis-infrastructure!223 (merged)

changed the description

added priority:normal label and removed priority:needs triage label

added release:v2025 label

added release:v2026dev0 release:v2026dev1 labels