docs(gatsby/seo): add Gatsby plugins to manage sitemap & canonical links

[tiloyi]

I have read the contributing guidelines

• [x] Yes
• [ ] No

Does this PR introduce a breaking change?

• [ ] Yes
• [x] No

Describe the changes

Add Gatsby plugins to manage sitemap & canonical links

GitHub issue number or Jira issue URL: N/A

Other information

[SimonCfn]

Checkmarx One – Scan Summary & Details – 9371671c-498a-4c0b-a57e-102d7d4358c7

Fixed Issues

Severity	Issue	Source File / Package
	CVE-2023-26159	Npm-follow-redirects-1.15.3
	CVE-2023-52079	Npm-msgpackr-1.10.0