Fix dpub/graphics/mathml/svg aam spec links to monorepo

[rahimabdi]

Describe the change

The following repo READMEs have broken links to their respective ARIA monorepo locations where it’s stated:
“To open a PR, please see the main ARIA repository where the specification lives”:

• dpub-aam
• graphics-aam
• mathml-aam
• svg-aam

Monorepo spec links to use for the "main ARIA repository where the specification lives" link:
⁃ dpub-aam: https://github.com/w3c/aria/tree/main/dpub-aam
⁃ graphics-aam: https://github.com/w3c/aria/tree/main/graphics-aam
⁃ mathml-aam: https://github.com/w3c/aria/tree/main/mathml-aam
⁃ svg-aam: https://github.com/w3c/aria/tree/main/svg-aam

No issues with these specs:

• accname (PR: w3c/accname#242)
• html-aam
• core-aam (PR w3c/core-aam#235)

[spectranaut]

Ah! Nice catch, ty Rahim. Can you review?

• w3c/dpub-aam#42
• w3c/graphics-aam#18
• w3c/mathml-aam#36
• w3c/svg-aam#37

[spectranaut]

Also I missed:

• w3c/graphics-aria#13
• w3c/dpub-aria#69

[rahimabdi]

All look good, thanks @spectranaut!

[spectranaut]

oh specifically @rahimabdi could you do an approving review on these PRs? ^ just so I don't get a warning when merging :)

[rahimabdi]

Done.