1189 tf topic guide

[RossKen]

Closes #1189

Shifting @samnlindsay's great guide on tf adjustments from confluence into the splink docs

[github-actions]

Test: test_2_rounds_1k_duckdb

Percentage change: -29.6%

	date	time	stats_mean	stats_min	commit_info_branch	commit_info_id	machine_info_cpu_brand_raw	machine_info_cpu_hz_actual_friendly	commit_hash
849	2022-07-12	18:40:05	1.89098	1.87463	splink3	c334bb9	Intel(R) Xeon(R) Platinum 8370C CPU @ 2.80GHz	2.7934 GHz	c334bb9
1620	2023-05-16	09:12:51	1.34098	1.31887	(detached head)	4c36008	Intel(R) Xeon(R) Platinum 8370C CPU @ 2.80GHz	2.7934 GHz	4c36008

Test: test_2_rounds_1k_sqlite

Percentage change: -25.4%

	date	time	stats_mean	stats_min	commit_info_branch	commit_info_id	machine_info_cpu_brand_raw	machine_info_cpu_hz_actual_friendly	commit_hash
851	2022-07-12	18:40:05	4.32179	4.25898	splink3	c334bb9	Intel(R) Xeon(R) Platinum 8370C CPU @ 2.80GHz	2.7934 GHz	c334bb9
1622	2023-05-16	09:12:51	3.17716	3.1755	(detached head)	4c36008	Intel(R) Xeon(R) Platinum 8370C CPU @ 2.80GHz	2.7934 GHz	4c36008

Click here for vega lite time series charts

[RossKen]

Given #1226 is taking a bit longer to finish off, merging this in now and can update docs with the function in a separate PR