Correct n_trials docs

[joaomcteixeira]

unless I am missing something critical n_trails will only be used if --mcsce-mode exhaustive. That's what I understood from MCSCE code and wrote in the docs. @JerryJohnsonLee help please 😉

In simple mode n_trials is also in effect, which is the maximum number of trials allowed before returning None, so increasing n_trials will make the success rate of difficult cases higher, but it also takes more time.

I am looking into the other issues.

Originally posted by @JerryJohnsonLee in #191 (comment)