README references a link in the wiki that doesn't exist.

[almamigratoria-netizen]

Problem:

README says "Guidelines for shortening codes are in the wiki."

That link is dead. Probably just failed to update something, but....

[jgrisham]

Here's the commit history for that link: https://github.com/google/open-location-code/commits/main/Documentation/Specification/Short_Code_Guidance.md

It appears the original page was moved / deleted in #590 and #597

Here's the last version of that page archived at the Wayback Machine: https://web.archive.org/web/20241127000820/https://github.com/google/open-location-code/blob/main/Documentation/Specification/Short_Code_Guidance.md