documentation for creating pool accounts on WNs

there is the need to document how to create pool accounts on WNs.
for example there is this old documentation that still refers to the good old YAIM:
https://twiki.cern.ch/twiki/bin/view/LCG/YaimGuide301#users_conf

In case of other middlware products, the creation of pool accounts could be automatic when enabling a VO, and the documentation could already exist, but it is worth to check if it is the case and to add a link to it

Review the linked YAIM users_conf documentation first, then check whether other middleware products create pool accounts automatically when a VO is enabled and whether current documentation already exists. Done means documenting the applicable creation process for WNs and adding links to relevant existing guidance.

Written by the indexing model from the issue text.