fvSolutions : algorithms beside simple

[yehudarav]

is it necessary to elaborate about other algorithms beside SIMPLE?

[yehudarav]

Generally yes. Document at least PIMPLE as well.

Others will be added in the future according to the specific solvers.

[NogaObs]

I added explanation about PISO and PIMPLE amd small comparison - but left the same data about the parameters. let me know if you want it differently