Prepare for the demo to present Custom field back-end and possibly front-end development to User Management SIG.

Additionally update the existing CF documentation to cover the topics raised in the comments to
https://folio-org.atlassian.net/browse/UXPROD-33. The list of topics should include but not limited to:

• 2 main areas:

  • definition

  • assignment

• integration into a module

  • what is common and what is not

  • explain that custom fields live inside a module and share its resources including DB

• field validation

  • during the definition

  • during the assignment

• performance concerns

  • how validation affects main operations with record