feature: improve doc on wizard specialize school

[dcpc007]

To create a wizard specialist there is a manipulation to do, but lacks some documentation. I try to list where i was lost because didn't find where to configure it or how.

• [ ] Wiki -> classes : no mention on specialized school (only in spells section)
• [ ] Wiki -> No doc on how-to configure the specialized school
• [ ] Ingame -> add a doc or link to a doc in the wizard specialist description text to explain to manipulation)
• [ ] Ingame -> when adding a school spe, confused, because no "specialized" mention, only "Conjuration Spell school", i didn't understand it was that at first glance
• [ ] Ingame -> school spe configuration : what to add in the forbid spell school ? which names and separator ? possible to add a text are a pop-up on an (?) icon with the tip/example ?
• [ ] ingame -> school spe configuration : the Spell School/Domain Spells block confuse me : it's only for domain spells.

[github-actions[bot]]

Thanks for opening an issue, traveller! If your issue is related to an actor or an item, sending thing that is broken will help a lot and speed up debugging.

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