Updating documentation

[f14m07]

Hi Franky,
I wanted to point out a small anomaly in the hook documentation.
The last line just before the 'Filters' section refers to a function
$member=eme_get_member_by_personid_membershipid($booking['person_id'],$membership_id);
which I haven't found.

[liedekef]

Corrected (removed from doc)