Update nav menu blog target to reference new blog subdomain

[TasoOneAsia]

Proposed Changes

Updated all existing nav menu links to reference the new blog.nginx.org subdomain (intended for OSS/Community specific usage) instead of nginx.com/blog.

These changes should ideally go live on 5/15/24, coinciding with the updated NGINX.com redirect rules planned to go into effect.

• blog.nginx.org is already live with the selection of posts targeted for migration
• On 5/15/24, NGINX.com will apply redirect rules for select blog posts targeted for migration towards blog.nginx.org

Additional Notes

Updated for all languages, regardless of their actual usage, as this was just a find & replace operation for nginx.com/blog -> blog.nginx.org

[TasoOneAsia]

@y82 appreciate the review as always. I've pushed up the amended message.

For my own future reference, the styling comment was related to using the present-tense instead of past-tense, right? If so, should that explicitly be mentioned in the styling semantics? Happy to submit a PR if helpful :)