Added json example for exponential histogram

[swamisriman]

Resolves #544

The exponential histogram datapoint in this commit, when sent to otel col, produces this log

Metric #0
Descriptor:
     -> Name: my.exponential.histogram
     -> Description: I am an Exponential Histogram
     -> Unit: 1
     -> DataType: ExponentialHistogram
     -> AggregationTemporality: Delta
ExponentialHistogramDataPoints #0
Data point attributes:
     -> my.exponential.histogram.attr: Str(some value)
StartTimestamp: 2018-12-13 14:51:00.3 +0000 UTC
Timestamp: 2018-12-13 14:51:00.3 +0000 UTC
Count: 3
Sum: 10.000000
Min: 0.000000
Max: 5.000000
Bucket [0, 0], Count: 1
Bucket (2.000000, 4.000000], Count: 0
Bucket (4.000000, 8.000000], Count: 2

The actual datapoint values are {0, 5, 5}

[linux-foundation-easycla]

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• ✅ login: swamisriman / name: Sriman Swami (826dd49)

[swamisriman]

Hi @reyang
Can you please review?

[reyang]

Hi @reyang Can you please review?

Done, thanks for your contribution @swamisriman!