Update README.md to swap ch 6 (opt) and ch 7 (inf) #978

Job	Run time
update_notebooks_md	27s
black_format_MUST_PASS	44s
static_import_check_MUST_PASS	1m 8s
execute_current_PR_notebooks_MUST_PASS	0s
execute_all_notebooks (0)	4m 30s
execute_all_notebooks (1)	4m 26s
execute_all_notebooks (2)	9m 6s
execute_all_notebooks (3)	4m 32s
execute_all_notebooks (4)	4m 20s
execute_all_notebooks (5)	4m 39s
execute_all_notebooks (6)	4m 30s
execute_all_notebooks (7)	4m 50s
execute_all_notebooks (8)	4m 39s
execute_all_notebooks (9)	4m 25s
execute_all_notebooks (10)	4m 45s
execute_all_notebooks (11)	4m 17s
execute_all_notebooks (12)	4m 32s
execute_all_notebooks (13)	4m 35s
execute_all_notebooks (14)	4m 54s
execute_all_notebooks (15)	4m 29s
execute_all_notebooks (16)	4m 37s
execute_all_notebooks (17)	4m 23s
execute_all_notebooks (18)	4m 18s
execute_all_notebooks (19)	4m 32s
combine_and_publish_results	1m 9s
	1h 38m 47s

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