Use the best tuner possible (#4397)
Use the best tuner possible (#4397)

* Use the best tuner possible

* Add comment denoting availability of better tuners

* Fix typos and wording

Laurawly/tvm-1,sxjscience/tvm,dmlc/tvm,Laurawly/tvm-1,Laurawly/tvm-1,Laurawly/tvm-1,Laurawly/tvm-1,tqchen/tvm,dmlc/tvm,sxjscience/tvm,tqchen/tvm,dmlc/tvm,dmlc/tvm,tqchen/tvm,Laurawly/tvm-1,sxjscience/tvm,sxjscience/tvm,sxjscience/tvm,tqchen/tvm,tqchen/tvm,sxjscience/tvm,Laurawly/tvm-1,sxjscience/tvm,dmlc/tvm,sxjscience/tvm,tqchen/tvm,tqchen/tvm,tqchen/tvm,Laurawly/tvm-1,dmlc/tvm,dmlc/tvm,dmlc/tvm,sxjscience/tvm,Laurawly/tvm-1,tqchen/tvm,tqchen/tvm,Laurawly/tvm-1,dmlc/tvm