docs: Update redirects for removed pages

[germartinez]

Context

This PR:

• Orders and fixes old redirects
• Redirects removed URLs to new ones with a conditional query param
• Displays the new callout

[github-actions]

Branch preview

✅ Deployed successfully in branch deployment:

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

[github-actions]

Overall readability score: 51.5 (🔴 -0.35)

File	Readability
onramp.mdx	48.99 (🔴 -2.35)
monerium.mdx	66.53 (🔴 -1.77)
stripe.mdx	49.01 (🔴 -1.39)
signers.mdx	45.27 (🔴 -26.75)

View detailed metrics

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

File	Readability	FRE	GF	ARI	CLI	DCRS
onramp.mdx	48.99	37.81	10.24	14.2	14.67	7.8
	🔴 -2.35	🔴 -7.44	🟢 +0.76	🔴 -0.4	🔴 -1.51	🟢 +0.09
monerium.mdx	66.53	49.31	8.6	10.4	11.77	6.8
	🔴 -1.77	🔴 -0.1	🔴 -0.09	🔴 -0.6	🔴 -0.47	🔴 -0.02
stripe.mdx	49.01	40.35	9.07	15.5	15.88	7.43
	🔴 -1.39	🟢 +0	🔴 -0.04	🔴 -0.5	🔴 -0.4	🔴 -0.01
signers.mdx	45.27	29.86	10.57	14.8	15.54	7.72
	🔴 -26.75	🔴 -26.69	🔴 -1.96	🔴 -5.8	🔴 -5.57	🔴 -0.84

Averages:

	Readability	FRE	GF	ARI	CLI	DCRS
Average	51.5	45.49	11.38	13.74	12.96	7.77
	🔴 -0.35	🔴 -0.38	🔴 -0.01	🔴 -0.08	🔴 -0.09	🔴 -0.01

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

[tanay1337]

Love it, great initiative! 🎖️