fix: prevent double-prefix in docsUrl by handling absolute URLs

[damitha-canva]

Ensure that documentation links use the base docs_url only for relative paths. Absolute URLs are now passed through unchanged, avoiding malformed URLs like:

https://lottie.github.io/lottie-spec/latest/https://…

[mbasaglia]

Maybe it's better to fix the root cause than the symptom, where have you encountered this?

[damitha-canva]

Coming from

https://lottie.github.io/validator/

Text =>

{"c":"k"}

url comes as https://lottie.github.io/lottie-spec/latest/https://lottie.github.io/lottie-spec/latest/specs/composition/#animation

I think it is reading the default_config from https://github.com/lottie/lottie-specs-js/blob/aab6b9fa491bc04c0790445864a920a0c1ca1faf/src/validator.js#L276

[mbasaglia]

The repo for that would be this: https://github.com/lottie/lottie-specs-js

But there too I think we should fix the core problem rather then matching the url

[damitha-canva]

Not sure what is the problem in lottie-spec-js though, I assume users want to use the docs_url when they use LottieValidator independently. I have made a commit to override the default_config in LottieValidator when used in this repo.