Remove unfinished sentence in sciml_train docs

[gileshd]

The first paragraph of the manual docs for sciml_train - sciml_train.md - has an unfinished sentence at the end:

sciml_train is a heuristic-based training function built using GalacticOptim.jl. It incorporates the knowledge of many high level benchmarks to attempt and do the right thing. However, if you need more control,

From the contents of this example I am guessing that the whole sentence was copied accidentally and can be removed.