Update 100-metrics.md (#6217)

* Update 100-metrics.md

Added some extra points to the metrics, which will give a bit more knowledge on the go.

* Update src/data/roadmaps/aws/content/108-cloudwatch/100-metrics.md

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Co-authored-by: dsh <daniel.s.holdsworth@gmail.com>

src/data/roadmaps/aws/content/108-cloudwatch/100-metrics.md

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 # Metrics
 
-In Amazon CloudWatch, **metrics** are fundamental concepts that you work with. A metric is the fundamental concept in CloudWatch and represents a time-ordered set of data points that are published to CloudWatch. Think of a metric as a variable to monitor, and the data points as representing the values of that variable over time. Metrics are uniquely defined by a name, a namespace, and zero or more dimensions. Every data point must have a timestamp. You can retrieve statistics about those data points as an ordered set of time-series data.
+In Amazon CloudWatch, **metrics** are fundamental concepts that you work with. A metric is the fundamental concept in CloudWatch and represents a time-ordered set of data points that are published to CloudWatch. Think of a metric as a variable to monitor, and the data points as representing the values of that variable over time. Metrics are uniquely defined by a name, a namespace, and zero or more dimensions up to 30 dimensions per metric. Every data point must have a timestamp. You can retrieve statistics about those data points as an ordered set of time-series data. CloudWatch provides metrics for every serviece in AWS.
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+Learn more from the following resources:
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+- [@official@CloudWatch Metrics](https://docs.aws.amazon.com/AmazonCloudWatch/latest/monitoring/publishingMetrics.html)