docs: update update.md to reflect install.sh delegation

Author: lifeofpavs

docs/update.md

@@ -1,6 +1,6 @@
 # Update
 
-Self-update the CLI to the latest version. Detects whether the CLI was installed via a package manager or as a standalone binary and acts accordingly.
+Self-update the CLI to the latest version.
 
 ## Usage
 
@@ -16,9 +16,7 @@ jup update --check
 
 1. Checks the latest release on GitHub
 2. Compares with the installed version
-3. If a newer version is available:
-   - **Package manager installs** — runs the appropriate update command (npm, pnpm, yarn, bun, or Volta)
-   - **Binary installs** — downloads the new binary, verifies its SHA-256 checksum, and atomically replaces the current binary
+3. If a newer version is available, fetches and runs `install.sh` which handles the update (Volta → npm → standalone binary fallback)
 4. Outputs the result
 
 ## JSON output
@@ -38,24 +36,14 @@ jup update --check
   "status": "update_available"
 }
 
-// Updated via package manager
+// Updated
 {
   "currentVersion": "0.3.0",
   "latestVersion": "0.4.0",
-  "status": "updated",
-  "method": "npm"
-}
-
-// Updated via binary
-{
-  "currentVersion": "0.3.0",
-  "latestVersion": "0.4.0",
-  "status": "updated",
-  "method": "binary"
+  "status": "updated"
 }
 ```
 
 ## Notes
 
-- Binary updates require write permission to the binary path. If you get a permission error, run `sudo jup update`.
-- Binary builds are available for: `linux-x64`, `linux-arm64`, `darwin-x64`, `darwin-arm64`.
+- Supported platforms: `linux-x64`, `linux-arm64`, `darwin-x64`, `darwin-arm64`.