Use `--set-param` hydra syntax for the `tune-hyperparams` branch

[daavoo]

Added Grid Search example here as I notice the first example was using the get-started. We could actually generate the example-get-started repo based on this example:

example-repos-dev/example-get-started/generate.sh

Lines 187 to 191 in cfa4ca4

	dvc exp run --queue --set-param train.min_split=8
	dvc exp run --queue --set-param train.min_split=64
	dvc exp run --queue --set-param train.min_split=2 --set-param train.n_est=100
	dvc exp run --queue --set-param train.min_split=8 --set-param train.n_est=100
	dvc exp run --queue --set-param train.min_split=64 --set-param train.n_est=100

Originally posted by @daavoo in iterative/dvc.org#3960 (comment)