Include examples

[nickevansuk]

British Cycling: https://github.com/openactive/activation/issues/104 Classfinder: https://github.com/openactive/activation/issues/113

[ldodds]

Just noting there are some bugs in those examples.

• activity should be an array
• use of eventSchedule is incorrect, its repeatFrequency not frequency and ideally should be a Duration, e.g. "P1W", "weekly" is not defined anywhere
• Some new properties, e.g. beta:activityDuration, beta:numberOfMembers which aren't referenced anywhere else
• distance is in Schema.org but is a property of an ExerciseAction or TravelAction not an Event
• programme refers to a Concept, but used here to refer to a Brand
• britishcycling:**** properties should be declared somewhere
• http://openactive.io/ns#Member is not defined anywhere