feat: add vanity for go.bytecodealliance.org

[ricochet]

We are moving the vanity url's to this repo where most go activity in the org will be maintained.

Step 1 for this move is to keep the current modules in place and working. As we need the package name, e.g. x, we will move that module to this repo.

componentize-go/docs/
  ├── CNAME           → go.bytecodealliance.org
  ├── index.html      → go-modules (legacy root)
  ├── cm.html         → go-modules (legacy cm module)
  ├── wit.html        → go-modules (legacy wit package)
  ├── x.html          → go-modules (legacy x package)
  ├── cmd.html        → go-modules (legacy cmd package)
  └── 404.html        → componentize-go (NEW packages - catch-all)

  How it works
  ┌──────────────────────────────────────┬───────────────────────────┐
  │             Import path              │        Resolves to        │
  ├──────────────────────────────────────┼───────────────────────────┤
  │ go.bytecodealliance.org              │ go-modules                │
  ├──────────────────────────────────────┼───────────────────────────┤
  │ go.bytecodealliance.org/cm           │ go-modules                │
  ├──────────────────────────────────────┼───────────────────────────┤
  │ go.bytecodealliance.org/wit          │ go-modules                │
  ├──────────────────────────────────────┼───────────────────────────┤
  │ go.bytecodealliance.org/x            │ go-modules                │
  ├──────────────────────────────────────┼───────────────────────────┤
  │ go.bytecodealliance.org/cmd/...      │ go-modules                │
  ├──────────────────────────────────────┼───────────────────────────┤
  │ go.bytecodealliance.org/anything-new │ componentize-go (via 404) │
  └──────────────────────────────────────┴───────────────────────────┘