Added PostgreSQL tutorial for beginners (#2506)

* feat: free content about ci/cd

add a read free content about ci/cd

* feat: add a postgre tutorial

Added PostgreSQL full tutorial for beginners in SQL

Thank you '-'

content/roadmaps/101-backend/content/106-relational-databases/100-postgresql.md

@@ -11,5 +11,6 @@ PostgreSQL, also known as Postgres, is a free and open-source relational databas
 <ResourceGroupTitle>Free Content</ResourceGroupTitle>
 <BadgeLink badgeText='Official Website' colorScheme="blue" href='https://www.postgresql.org/'>Official Website</BadgeLink>
 <BadgeLink badgeText='Read' colorScheme="yellow" href='https://www.geeksforgeeks.org/what-is-postgresql-introduction/'>What is PostgreSQL</BadgeLink>
+<BadgeLink colorScheme='yellow' badgeText='Read' href='https://www.postgresqltutorial.com/'>Learn PostgreSQL - Full Tutorial for Beginners</BadgeLink>
 <BadgeLink badgeText='Watch' href='https://www.youtube.com/watch?v=qw--VYLpxG4'>Learn PostgreSQL Tutorial - Full Course for Beginners</BadgeLink>
 <BadgeLink badgeText='Watch' href='https://www.youtube.com/watch?v=eMIxuk0nOkU'>Postgres tutorial for Beginners</BadgeLink>