Re: Doc fix of aggressive vacuum threshold for multixact members storage

> A few paragraphs up the docs, there is this mention:
>
> ". There is a separate storage area which holds the list of members
> in each multixact, which also uses a 32-bit counter and which must
> also be managed."
>
> Maybe we can add more to this paragraph, such as:
>
> "also be managed. This member can grow to 20GB"
>
> And then in the proposed correction:
>
> "
> Also, if the storage occupied by multixacts members area exceeds 10GB
> (50% of the maximum the members area can grow), aggressive vacuum
> scans will occur more often for all tables
> "
>
> What do you think?
>

Looks good to me, attached a v2 patch with small adjustments.

Thanks,

Alex