Add observability tools to "Tools and Libraries" page

> Let's use this opportunity to add a section to https://graphql.org/community/tools-and-libraries/ around observability and link here to that section so people can go and see specific solutions around that

_Originally posted by @Urigo in https://github.com/graphql/graphql.github.io/pull/1818#discussion_r1843944175_

Start with the existing Tools and Libraries page at https://graphql.org/community/tools-and-libraries/ and review its current section structure and linked entries. Define the observability section's scope with the maintainers, then add the section and link to it from the issue; done means the page presents specific observability solutions clearly.

Written by the indexing model from the issue text.