Update comment in trust_region_minimizer.h.
Update comment in trust_region_minimizer.h.

Update comment to better reflect the Minimizer API.

Change-Id: Icca1d41fdea1f8dacde2e1af3239486820ef2b7f

ysonggit/ceres-solver,ikoruk/ceres-solver,DougFirErickson/ceres-solver,entylop/ceres-solver,timfel/ceres-bin,stonier/ceres_solver,DougFirErickson/ceres-solver,stonier/ceres_solver,kartikkumar/ceres-solver,stonier/ceres_solver,timfel/ceres-bin,kartikkumar/ceres-solver,jmwalls/ceres-solver-fork,DougFirErickson/ceres-solver,kartikkumar/ceres-solver,ikoruk/ceres-solver,DougFirErickson/ceres-solver,jmwalls/ceres-solver-fork,ysonggit/ceres-solver,whuaegeanse/ceres-solver,timfel/ceres-bin,ysonggit/ceres-solver,entylop/ceres-solver,jmwalls/ceres-solver-fork,ikoruk/ceres-solver,timfel/ceres-bin,stonier/ceres_solver,jmwalls/ceres-solver-fork,ysonggit/ceres-solver,ikoruk/ceres-solver,entylop/ceres-solver,kartikkumar/ceres-solver,whuaegeanse/ceres-solver,whuaegeanse/ceres-solver,entylop/ceres-solver,whuaegeanse/ceres-solver,ikoruk/ceres-solver