Broken links on https://webassembly.org/docs/portability/

[jmillikin]

IEEE 754-2008 32-bit and 64-bit floating point, except for a few exceptions.

Link https://webassembly.org/docs/semantics/#floating-point-operators redirects to https://webassembly.github.io/spec/core/exec/index.html#floating-point-operators, which is a table of contents.

The correct link / redirect would be https://webassembly.github.io/spec/core/exec/numerics.html#floating-point-operations -- note that the anchor also changed.

wasm64 additionally supports linear memory bigger than 4 GiB with 64-bit pointers or indices.

Link https://webassembly.org/docs/future-features/#linear-memory-bigger-than-4-gib redirects to https://webassembly.org/roadmap/#linear-memory-bigger-than-4-gib, which doesn't have any element with a matching id=. Changing the link to https://github.com/WebAssembly/memory64/blob/master/proposals/memory64/Overview.md might be better, or alternatively using a non-GitHub stable URL if one is available for that proposal.

the host environment’s available imports either at compile-time (via #ifdef) or run-time (via feature detection and

Link https://webassembly.org/docs/feature-test/ redirects to https://webassembly.org/roadmap/, which doesn't seem to have any content related to feature detection. Maybe the link could be updated to point at a proposal, if one is active?