[fpc-pascal] FPC Docs updated

[Marco van de Voort]

In our previous episode, Graeme Geldenhuys said:
> > Why, were you expecting some changes ?
> 
> Not too important or urgent, but I know I sumitted some Language Ref
> changes to Mantis, and they are not yet in the latest docs.
> 
> Anyway, I first need to complete the Lang Ref doc for INF, then I'll get
> the latest docs from SVN and update the INF doc were needed.
> 
> PS:
> I can't remember all the lang ref changes I submitted, but I do remember
> one of them was about UnicodeString type - currently not mentioned in the
> ref document.

I only fixed spelling and formatting issues, not content.