Using the same default buckets as other libraries

[isaacsanders]

Hey all,

I would like to suggest that we use a default value for our buckets that other libraries use.

Python

https://github.com/prometheus/client_python/blob/5a5261dd45d65914b5e3d8225b94d6e0578882f3/prometheus_client/metrics.py#L544

DEFAULT_BUCKETS = (.005, .01, .025, .05, .075, .1, .25, .5, .75, 1.0, 2.5, 5.0, 7.5, 10.0, INF)

Golang

https://github.com/prometheus/client_golang/blob/66837e3298bdc57a828794c23bacb253ed8c04cd/prometheus/histogram.go#L68

DefBuckets = []float64{.005, .01, .025, .05, .1, .25, .5, 1, 2.5, 5, 10}

Java

https://github.com/prometheus/client_java/blob/6ae0c961cfc19b8ef0575c98ac82ee55b11002ed/simpleclient/src/main/java/io/prometheus/client/Histogram.java#L88

private double[] buckets = new double[] { .005, .01, .025, .05, .075, .1, .25, .5, .75, 1, 2.5, 5, 7.5, 10 };

Overlap

Value	Duration	Python	Golang	Java
0.005	5ms	Yes	Yes	Yes
0.01	10ms	Yes	Yes	Yes
0.025	25ms	Yes	Yes	Yes
0.05	50ms	Yes	Yes	Yes
0.075	75ms	Yes	No	Yes
0.1	100ms	Yes	Yes	Yes
0.25	250ms	Yes	Yes	Yes
0.5	500ms	Yes	Yes	Yes
0.75	750ms	Yes	No	Yes
1.0	1s	Yes	Yes	Yes
2.5	2.5s	Yes	Yes	Yes
5.0	5s	Yes	Yes	Yes
7.5	7.5s	Yes	No	Yes
10.0	10s	Yes	Yes	Yes

[bryannaegele]

I think that's fine if you want to do a PR