Update Postgres to PostgreSQL in charts repo
Fixing instances of 'Postgres' in text to 'PostgreSQL' in the charts repository.
Related to gitlab-org/gitlab!27764 (merged) where we are fixing things in the main gitlab
repository
Related to gitlab-org/gitlab!25944 (merged) where we started building spelling rules, including favoring PostgreSQL
instead of Postgres
Edited by 🤖 GitLab Bot 🤖