docs: winget package is published

[zcsizmadia]

wslkit.skrog 0.8.0 is published on winget (microsoft/winget-pkgs#436048, merged 2026-10-13, publish pipeline succeeded).

Changes

• README: winget install wslkit.skrog sits beside the install script and scoop. The two "a winget package is on the way" lines are updated. "What's ahead" now names signing and the MSI.
• docs/install.md:
  • New "Or with winget" section, including that winget can trail a release while its manifest is in review.
  • New "Pick one way to install" section.
  • The upgrade and uninstall sections name the winget and scoop commands.

Verified on a real machine

• winget install wslkit.skrog, from the published source: hash verified and the alias was created. Through the alias, skrog version reports 0.8.0. skrog autostart enable writes the Run entry to WinGet\Packages\…\skrogw.exe, which exists, so the os.Executable() is used to find sibling files, which breaks behind a symlink shim (winget portable) #360 regression is not present.
• Same checks on a local 0.10.0 manifest (winget install --manifest): it reports 0.10.0, and autostart resolves into the package directory.
• The "pick one way" section describes what happened on this machine. After an earlier script install, winget install left two copies, and plain skrog kept running the script's copy because %LOCALAPPDATA%\Programs\skrog comes before WinGet\Links on the user PATH. That the install script appends to PATH is from scripts/install.ps1:170.

Not verified on a real install

• skrog upgrade --apply refusing under winget is read from the code (cmd/skrog/upgrade.go:375, internal/upgrade/owner.go) and covered by owner_test.go. It wasn't run through a winget install. The refusal only fires when the app is behind, and on this machine an older winget copy would have meant --apply upgrading the real engine first. That ordering is a follow-up question: under winget, --apply applies the engine and CLI steps and then refuses the app.
• That scoop appends to PATH was not checked, so the text only says it about the script and winget.

Closes #412