The first step is for you to provide the details for the additions, ideally asa code patch against the website repository [0]. Personally I don't see thevalue in adding books which were written and printed for a version of postgreswhich is now out of support (like "Beginning PostgreSQL on the cloud" whichcame out in 2018), but others may disagree.
pgsql-www by date:
Соглашаюсь с условиями обработки персональных данных