docs: Add migration guide from v4 to v5 to protocol-kit docs

[DaniSomoza]

Add migration guide from v4 to v5 to protocol-kit docs

[github-actions]

Branch preview

✅ Deployed successfully in branch deployment:

https://protocol_kit_migrate_to_v5--docs.review.5afe.dev

[github-actions]

Overall readability score: 38.84 (🟢 +0.05)

File	Readability
migrate-to-v5.md	46.06 (-)

View detailed metrics

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

File	Readability	FRE	GF	ARI	CLI	DCRS
migrate-to-v5.md	46.06	38.01	13	12.8	13.86	8.24
	-	-	-	-	-	-

Averages:

	Readability	FRE	GF	ARI	CLI	DCRS
Average	38.84	34.27	12.57	16.55	14.83	8.4
	🟢 +0.05	🟢 +0.02	🟢 +0	🟢 +0.02	🟢 +0.01	🟢 +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