Ensure patch version is provided if accessing versioned documentation

[nain-F49FF806]

This is step one in addressing https://github.com/rust-lang/simpleinfra/issues/360

Have modified the router slightly

• If complete (including patch) version provided, forward as is
• If only upto minor version is provided, redirect to patch zero of that minor version

This should help in redirecting minor version documentation access to (hopefully) valid pages

Todo/Future: Consider forwarding to latest patch when only minor version provided