Update TOML description to include version number #123905

There is some movement, currently blocked, that would update the TOML spec to 1.1.0; this would include breaking changes to what characters are allowed. Thus, it is worthwhile for the library page to be clear which version is implemented here.

Linked PRs

• gh-123905: Update TOML description to include version number #123825
• gh-123905: Update TOML description to include version number #123906
• [3.12] gh-123905: Update TOML description to include version number (GH-123906) #123907
• [3.13] gh-123905: Update TOML description to include version number (GH-123906) #123908