chore: update link to ECHO documentation

[richardapeters]

No description provided.

[github-actions]

🦙 MegaLinter status: ⚠️ WARNING

Descriptor	Linter	Files	Fixed	Errors	Elapsed time
✅ ACTION	actionlint	4		0	0.02s
✅ DOCKERFILE	hadolint	1		0	0.12s
✅ JSON	prettier	6	1	0	0.74s
✅ JSON	v8r	6		0	4.49s
⚠️ MARKDOWN	markdownlint	8	1	3	0.89s
⚠️ MARKDOWN	markdown-link-check	8		6	3.36s
✅ MARKDOWN	markdown-table-formatter	8	1	0	0.46s
✅ REPOSITORY	checkov	yes		no	14.88s
✅ REPOSITORY	git_diff	yes		no	0.09s
✅ REPOSITORY	grype	yes		no	9.43s
✅ REPOSITORY	secretlint	yes		no	1.45s
✅ REPOSITORY	trivy	yes		no	5.15s
✅ REPOSITORY	trivy-sbom	yes		no	0.07s
✅ REPOSITORY	trufflehog	yes		no	2.29s
⚠️ SPELL	lychee	36		9	0.59s
✅ YAML	prettier	8	0	0	0.71s
✅ YAML	v8r	8		0	6.06s
✅ YAML	yamllint	8		0	0.42s

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