adding email duplication restriction info accross docs

[RaquelHipolito]

👀 Live preview

🚧 To do

• If relevant, include the Jira issue key at the end of the pull request title
• Perform a self-review of the changes
• Fix any issues reported by the CI/CD

[github-actions]

Overall readability score: 53.65 (🔴 -0.01)

File	Readability
emails.md	50.97 (🟢 +0.51)
managing-people.md	45.28 (🔴 -2.66)

View detailed metrics

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

File	Readability	FRE	GF	ARI	CLI	DCRS
emails.md	50.97	40.08	12.02	14.7	12.65	7.01
	🟢 +0.51	🔴 -0.1	🟢 +0.12	🔴 -0.1	🟢 +0.06	🟢 +0.12
managing-people.md	45.28	21.33	11.93	16.4	13.87	6.56
	🔴 -2.66	🔴 -1.32	🔴 -0.6	🔴 -0.7	🔴 -0.17	🔴 -0.05

Averages:

	Readability	FRE	GF	ARI	CLI	DCRS
Average	53.65	42.74	10.85	12.54	12.6	7.94
	🔴 -0.01	🔴 -0.01	🟢 +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

[machadoit]

LGTM!