Free count hackney pool metric is sending a wrong type

[indrekj]

README says that hackney.POOLNAME.free_count is a counter. doc/overview.md says that hackney.POOLNAME.free_count is a counter. The metric however is initialized and updated as a histogram.

I'm not sure if either of them actually are correct. Counters are meant for values that are increasing (e.g. successful login count). Histograms are usually used for things like request durations or response sizes. Here we're checking a metric that can fluctuate over time. Shouldn't it be a gauge?

[benoitc]

i agree. should be fixed.