Add 'count' to the achievement with the given name. This must be a COUNT achievement. The largest number that is supported by this method is the max value of a signed 64-bit integer. If the number is larger than that, it is clamped to that max value before being passed to the servers.
ParametersnameThe api_name of the achievement that will be adding count.
countThe value of count that will be added to the achievement.