Unnecessary hard coded precision in `HumanFloatCount`

[ReagentX]

The following is impossible to disable:

indicatif/src/format.rs

Line 157 in 14b5ef2

let num = format!("{:.4}", self.0);

This precision should be customizable. There is also nothing in the template docs that explain this.

[djc]

Sure, would you be able to submit a PR?