DOC: config: stick-table converter do accept ANY-typed input

DOC: config: stick-table converter do accept ANY-typed input

Since 2d17db58 ("MINOR: stick-table: change all stick-table converters'
inputs to SMP_T_ANY"), all stick-table converters accept ANY input
type as parameter, this means that it does no longer restrict the key as
a string representation of the input. However the doc wasn't updated when
the change was made. Moreover, some converters document the updated behavior
while others don't, which is kind of confusing, let's fix that.