DOC-1106: Update Slack UI labels

[freakwriter]

They've changed the UI layout a bit. This PR adjusts the steps and labels to match.

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[github-actions[bot]]

Overall readability score: 43.82 (🟢 +0)

File	Readability
slack.md	78.41 (🟢 +1.8)

View detailed metrics

🟢 - Shows an increase in readability 🔴 - Shows a decrease in readability

File	Readability	FRE	GF	ARI	CLI	DCRS
slack.md	78.41	60.61	6.18	8.9	10.48	6.22
	🟢 +1.8	🟢 +0.71	🟢 +0.31	🟢 +0.5	🟢 +0.23	🟢 +0.03

Averages:

	Readability	FRE	GF	ARI	CLI	DCRS
Average	43.82	35.23	11.53	14.78	14.3	8.49
	🟢 +0	🟢 +0	🟢 +0	🟢 +0	🟢 +0	🟢 +0

View metric targets

Metric	Range	Ideal score
Flesch Reading Ease	100 (very easy read) to 0 (extremely difficult read)	60
Gunning Fog	6 (very easy read) to 17 (extremely difficult read)	8 or less
Auto. Read. Index	6 (very easy read) to 14 (extremely difficult read)	8 or less
Coleman Liau Index	6 (very easy read) to 17 (extremely difficult read)	8 or less
Dale-Chall Readability	4.9 (very easy read) to 9.9 (extremely difficult read)	6.9 or less

[freakwriter]

@imchairmanm this should be a quick review, just updating the Slack credentials to reflect the UI changes they've rolled out.