Add note on Philip Astley.

Session/AstleysRide.abc

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 X:1
 T:Astley's Ride
+H:Dottes: Philip Astley's _Ride_ was a circular arena in which the famous
+H:+ equestrian demonstrated his trick riding skills. When, in 1770, he
+H:+ added jugglers, acrobats and a clown to his show, he invented an art
+H:+ form that spread rapidly around the world. Though as often happens
+H:+ with inventors, it was his imitator and rival Charles Bibdin who
+H:+ gave it the name we know today; the circus.
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 Q:180
 K:G