Various changes to groups.md 
Various changes to groups.md 

Changes to match updated welcome pack insert:  changed Smith group to Laithwaite; dropped Waterson & Crossley group; changed Huggard & Hall group to Hall only; changed Tanner & White group to Tanner only and added to description; added Judy Marshall group; other minor changes.
Cogges/cogges.github.io,Cogges/cogges.github.io