Typo in the documentation of MBH

**Describe the bug**
There is a typo in the pseudo code of MBH. The counter i should be equal to 0 when the best individual is improved and increase when
it is not. Indeed the stop_criteria is the maximum run of the UDA such that the best individual is not improved.
How I would modify the pseudo code:
```
> Select a pygmo population
> Select a UDA
> Store best individual
> while i < stop_criteria
> > Perturb the population in a selected neighbourhood
> > Evolve the population using the algorithm
> > if the best individual is improved
> > > update best individual
> > > i=0
> > else
> > > increment i
```
**Additional context**
Not sure if a typo can be considered a bug. If not, sorry for reporting it as a bug.