Incorrect default rate limit on CloudWatch input

[cosmopetrich]

Bug report

The documentation for the CloudWatch input notes that:

Maximum requests per second. Note that the global default AWS rate limit is
10 reqs/sec, so if you define multiple namespaces, these should add up to a
maximum of 10. Optional - default value is 10.

Is this actually correct? The AWS service limits documentation describes the following limits.

GetMetricStatistics - 400 transactions per second (TPS)
ListMetrics - 25 transactions per second (TPS)

The page linked in a comment shows the same limits. I can't find any information on a specific global rate other than a note that there's a vague per-region rate. Where did the figure of 10 come from? Is it possible that there was some confusion with the GetLogEvents limit, which was 10 at the time the rate limit feature was added?

[sparrc]

that could be, it's possible that AWS increased their limits.

If you want to change this please just submit a PR