Add a description how to update a record with a lookup in a free form

[YuliyaPoznyak]

No description provided.

[georged]

We need to explain the syntax for the lookup column value. It's either table:guid (for compatibility reasons) or serialised lookup (recommended) value = '{"LogicalName": "account", "Id": "{{accountid}}" }' %}. Cleaner syntax is probably using twig variable

{% set accountref = {"LogicalName": "account", "Id":  accountid } %}
<input value='{{accountref}}' ... >

Give validated examples of both. Confirm with Max which table name we need to use in the first (logical or schema).

Also, add a section about setting default values on the form if we don't have one already, most popular being a marketing form with hidden fields like source of lead (choice/optionset) and current user to set as an owner. Maybe that should be a KB as a real example.